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Sample records for ross river glycoprotein-pseudotyped

  1. Genetic heterogeneity among isolates of Ross River virus from different geographical regions.

    PubMed Central

    Lindsay, M D; Coelen, R J; Mackenzie, J S

    1993-01-01

    The RNase T1 maps of 80 isolates of Ross River virus from different regions of mainland Australia and the Pacific Islands were compared. Four different clusters of isolates with greater than an estimated 5 to 6% diversity at the nucleotide level were found. There was a pattern of differences between eastern and western Australian strains; however, the pattern was disturbed by overlaps and incursants. Pacific Islands isolates belonged to the eastern Australian topotype. Our findings suggest that certain genetic types of Ross River virus predominate in different geographical regions. In contrast, populations of other important Australian arboviruses (Murray Valley encephalitis, Kunjin, and Sindbis viruses) are distributed across the Australian continent as minor variants of one strain. Our data also show that in one region, strains of Ross River virus with identical RNase T1 maps circulate during both years when epidemics occur and years when they do not. This finding suggests that Ross River virus epidemics are not dependent on the introduction or evolution of new strains of the virus. Two strains, belonging to the eastern Australian topotype, were isolated in Western Australia. It is likely that viremic humans or possibly domestic livestock travelling by aircraft were responsible for this movement. Images PMID:8497065

  2. Heparin binding sites on Ross River virus revealed by electron cryo-microscopy

    SciTech Connect

    Zhang Wei; Heil, Marintha; Kuhn, Richard J.; Baker, Timothy S. . E-mail: tsb@chem.ucsd.edu

    2005-02-20

    Cell surface glycosaminoglycans play important roles in cell adhesion and viral entry. Laboratory strains of two alphaviruses, Sindbis and Semliki Forest virus, have been shown to utilize heparan sulfate as an attachment receptor, whereas Ross River virus (RRV) does not significantly interact with it. However, a single amino acid substitution at residue 218 in the RRV E2 glycoprotein adapts the virus to heparan sulfate binding and expands the host range of the virus into chicken embryo fibroblasts. Structures of the RRV mutant, E2 N218R, and its complex with heparin were determined through the use of electron cryo-microscopy and image reconstruction methods. Heparin was found to bind at the distal end of the RRV spikes, in a region of the E2 glycoprotein that has been previously implicated in cell-receptor recognition and antibody binding.

  3. Environmental drivers of Ross River virus in southeastern Tasmania, Australia: towards strengthening public health interventions.

    PubMed

    Werner, A K; Goater, S; Carver, S; Robertson, G; Allen, G R; Weinstein, P

    2012-02-01

    In Australia, Ross River virus (RRV) is predominantly identified and managed through passive health surveillance. Here, the proactive use of environmental datasets to improve community-scale public health interventions in southeastern Tasmania is explored. Known environmental drivers (temperature, rainfall, tide) of the RRV vector Aedes camptorhynchus are analysed against cumulative case records for five adjacent local government areas (LGAs) from 1993 to 2009. Allowing for a 0- to 3-month lag period, temperature was the most significant driver of RRV cases at 1-month lag, contributing to a 23·2% increase in cases above the long-term case average. The potential for RRV to become an emerging public health issue in Tasmania due to projected climate changes is discussed. Moreover, practical outputs from this research are proposed including the development of an early warning system for local councils to implement preventative measures, such as public outreach and mosquito spray programmes. PMID:21439102

  4. Epidemiologic patterns of Ross River virus disease in Queensland, Australia, 2001-2011.

    PubMed

    Yu, Weiwei; Mengersen, Kerrie; Dale, Pat; Mackenzie, John S; Toloo, Ghasem Sam; Wang, Xiaoyu; Tong, Shilu

    2014-07-01

    Ross River virus (RRV) infection is a debilitating disease that has a significant impact on population health, economic productivity, and tourism in Australia. This study examined epidemiologic patterns of RRV disease in Queensland, Australia, during January 2001-December 2011 at a statistical local area level. Spatio-temporal analyses were used to identify the patterns of the disease distribution over time stratified by age, sex, and space. The results show that the mean annual incidence was 54 per 100,000 persons, with a male:female ratio of 1:1.1. Two space-time clusters were identified: the areas adjacent to Townsville, on the eastern coast of Queensland, and the southeast areas. Thus, although public health intervention should be considered across all areas in which RRV occurs, it should specifically focus on high-risk regions, particularly during summer and autumn to reduce the social and economic impacts of RRV infection. PMID:24799374

  5. Meloxicam-induced rhabdomyolysis in the context of an acute ross river viral infection.

    PubMed

    Al Kindi, Mahmood; Limaye, Vidya; Hissaria, Pravin

    2012-01-01

    Acute rhabdomyolysis is a clinical and laboratory syndrome resulting from the breakdown of skeletal muscle, with the release of intracellular contents into the circulatory system, which can cause potentially lethal complications. Here, we present the case of a patient who developed acute rhabdomyolysis after consumption of meloxicam for jaw pain and experienced generalized myalgias in the context of an acute febrile illness with generalized urticaria. Further investigation indicated elevated muscle enzymes and acute renal failure. Serological analysis revealed that the patient was positive for Ross River virus (RRV) IgM. Genetic studies to detect CYP2C9 polymorphisms were negative. Meloxicam was discontinued. He responded to conservative measures within 2 weeks. Oral aspirin challenge was negative, suggesting a drug-specific effect of meloxicam rather than a class effect. Our case indicates a causative role for meloxicam and/or acute RRV in rhabdomyolysis. PMID:22211172

  6. Ross River Virus Transmission, Infection, and Disease: a Cross-Disciplinary Review

    PubMed Central

    Harley, David; Sleigh, Adrian; Ritchie, Scott

    2001-01-01

    Ross River virus (RRV) is a fascinating, important arbovirus that is endemic and enzootic in Australia and Papua New Guinea and was epidemic in the South Pacific in 1979 and 1980. Infection with RRV may cause disease in humans, typically presenting as peripheral polyarthralgia or arthritis, sometimes with fever and rash. RRV disease notifications in Australia average 5,000 per year. The first well-described outbreak occurred in 1928. During World War II there were more outbreaks, and the name epidemic polyarthritis was applied. During a 1956 outbreak, epidemic polyarthritis was linked serologically to a group A arbovirus (Alphavirus). The virus was subsequently isolated from Aedes vigilax mosquitoes in 1963 and then from epidemic polyarthritis patients. We review the literature on the evolutionary biology of RRV, immune response to infection, pathogenesis, serologic diagnosis, disease manifestations, the extraordinary variety of vertebrate hosts, mosquito vectors, and transmission cycles, antibody prevalence, epidemiology of asymptomatic and symptomatic human infection, infection risks, and public health impact. RRV arthritis is due to joint infection, and treatment is currently based on empirical anti-inflammatory regimens. Further research on pathogenesis may improve understanding of the natural history of this disease and lead to new treatment strategies. The burden of morbidity is considerable, and the virus could spread to other countries. To justify and design preventive programs, we need accurate data on economic costs and better understanding of transmission and behavioral and environmental risks. PMID:11585790

  7. Role of envelope N-linked glycosylation in Ross River virus virulence and transmission.

    PubMed

    Nelson, Michelle A; Herrero, Lara J; Jeffery, Jason A L; Hoehn, Marion; Rudd, Penny A; Supramaniam, Aroon; Kay, Brian H; Ryan, Peter A; Mahalingam, Suresh

    2016-05-01

    With an expanding geographical range and no specific treatments, human arthritogenic alphaviral disease poses a significant problem worldwide. Previous in vitro work with Ross River virus (RRV) demonstrated that alphaviral N-linked glycosylation contributes to type I IFN (IFN-αβ) induction in myeloid dendritic cells. This study further evaluated the role of alphaviral N-linked glycans in vivo, assessing the effect of glycosylation on pathogenesis in a mouse model of RRV-induced disease and on viral infection and dissemination in a common mosquito vector, Aedes vigilax. A viral mutant lacking the E1-141 glycosylation site was attenuated for virus-induced disease, with reduced myositis and higher levels of IFN-γ induction at peak disease contributing to improved viral clearance, suggesting that glycosylation of the E1 glycoprotein plays a major role in the pathogenesis of RRV. Interestingly, RRV lacking E2-200 glycan had significantly reduced replication in the mosquito vector A. vigilax, whereas loss of either of the E1 or E2-262 glycans had little effect on the competence of the mosquito vector. Overall, these results indicate that glycosylation of the E1 and E2 glycoproteins of RRV provides important determinants of viral virulence and immunopathology in the mammalian host and replication in the mosquito vector. PMID:26813162

  8. CD8+ T cells control Ross River virus infection in musculoskeletal tissues of infected mice.

    PubMed

    Burrack, Kristina S; Montgomery, Stephanie A; Homann, Dirk; Morrison, Thomas E

    2015-01-15

    Ross River virus (RRV), chikungunya virus, and related alphaviruses cause debilitating polyarthralgia and myalgia. Mouse models of RRV and chikungunya virus have demonstrated a role for the adaptive immune response in the control of these infections. However, questions remain regarding the role for T cells in viral control, including the magnitude, location, and dynamics of CD8(+) T cell responses. To address these questions, we generated a recombinant RRV expressing the H-2(b)-restricted glycoprotein 33 (gp33) determinant derived from the glycoprotein of lymphocytic choriomeningitis virus. Using tetramers, we tracked gp33-specific CD8(+) T cells during RRV-lymphocytic choriomeningitis virus infection. We found that acute RRV infection induces activation of CD8(+) T cell responses in lymphoid and musculoskeletal tissues that peak from 10-14 d postinoculation, suggesting that CD8(+) T cells contribute to control of acute RRV infection. Mice genetically deficient for CD8(+) T cells or wild-type mice depleted of CD8(+) T cells had elevated RRV loads in skeletal muscle tissue, but not joint-associated tissues, at 14 d postinoculation, suggesting that the ability of CD8(+) T cells to control RRV infection is tissue dependent. Finally, adoptively transferred T cells were capable of reducing RRV loads in skeletal muscle tissue of Rag1(-/-) mice, indicating that T cells can contribute to the control of RRV infection in the absence of B cells and Ab. Collectively, these data demonstrate a role for T cells in the control of RRV infection and suggest that the antiviral capacity of T cells is controlled in a tissue-specific manner. PMID:25488988

  9. The Quasi-Biennial Oscillation and Ross River virus incidence in Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Done, Sinead; Holbrook, Neil; Beggs, Paul

    2002-06-01

    Ross River virus (RRV) is the most important vector-borne disease in Australia. The National Notifiable Diseases Surveillance System has confirmed that its incidence is often greatest in the state of Queensland, where there is a clear seasonal pattern as well as interannual variability. Previous studies have examined relationships between large-scale climate fluctuations (such as El Niño Southern Oscillation) and vector-borne disease. No previous study has examined such relationships with the Quasi-Biennial Oscillation (QBO), another large-scale climate fluctuation. We employ time-series analysis techniques to investigate cycles inherent in monthly RRV incidence in Queensland, Australia, from January 1991 to December 1997 inclusive. The presence of a quasi-biennial cycle in the RRV time series that is out of phase with the climatic QBO is described. Quantitative analyses using correlograms and periodograms demonstrate that the quasi-biennial cycle in the RRV time series is statistically significant, at the 95% level, above the noise. Together with the seasonal cycle, the quasi-biennial cycle accounts for 77% of the variance in Queensland RRV cases. Regression analysis of QBO and summer rainfall in three climatic zones of Queensland indicates a significant association between QBO and rainfall in the subtropical southeastern part of the state. These results suggest an indirect influence of the QBO on RRV incidence in Queensland, via its influence on climate in this region. Our findings indicate that the QBO may be a useful predictor of RRV at several months lead, and might be used by public health authorities in the management and prevention of this disease.

  10. CD8+ T cells control Ross River virus infection in musculoskeletal tissues of infected mice

    PubMed Central

    Burrack, Kristina S.; Montgomery, Stephanie A.; Homann, Dirk; Morrison, Thomas E.

    2014-01-01

    Ross River virus (RRV), chikungunya virus (CHIKV), and related alphaviruses cause debilitating polyarthralgia and myalgia. Mouse models of RRV and CHIKV have demonstrated a role for the adaptive immune response in the control of these infections. However, questions remain regarding the role for T cells in viral control, including the magnitude, location, and dynamics of CD8+ T cell responses. To address these questions, we generated a recombinant RRV expressing the H-2b-restricted gp33 determinant derived from the glycoprotein (gp) of lymphocytic choriomeningitis virus (LCMV) (“RRV-LCMV”). Utilizing tetramers, we tracked gp33-specific CD8+ T cells during RRV-LCMV infection. We found that acute RRV infection induces activation of CD8+ T cell responses in lymphoid and musculoskeletal tissues that peak from 10 to 14 days post-inoculation (dpi), suggesting that CD8+ T cells contribute to control of acute RRV infection. Mice genetically deficient for CD8+ T cells or wild-type mice depleted of CD8+ T cells had elevated RRV loads in skeletal muscle tissue, but not joint-associated tissues, at 14 dpi, suggesting that the ability of CD8+ T cells to control RRV infection is tissue-dependent. Finally, adoptively transferred T cells were capable of reducing RRV loads in skeletal muscle tissue of Rag1−/− mice, indicating that T cells can contribute to the control of RRV infection in the absence of B cells and antibody. Collectively, these data demonstrate a role for T cells in the control of RRV infection and suggest that the antiviral capacity of T cells is controlled in a tissue-specific manner. PMID:25488988

  11. Projecting the impact of climate change on the transmission of Ross River virus: methodological challenges and research needs.

    PubMed

    Yu, W; Dale, P; Turner, L; Tong, S

    2014-10-01

    Ross River virus (RRV) is the most common vector-borne disease in Australia. It is vitally important to make appropriate projections on the future spread of RRV under various climate change scenarios because such information is essential for policy-makers to identify vulnerable communities and to better manage RRV epidemics. However, there are many methodological challenges in projecting the impact of climate change on the transmission of RRV disease. This study critically examined the methodological issues and proposed possible solutions. A literature search was conducted between January and October 2012, using the electronic databases Medline, Web of Science and PubMed. Nineteen relevant papers were identified. These studies demonstrate that key challenges for projecting future climate change on RRV disease include: (1) a complex ecology (e.g. many mosquito vectors, immunity, heterogeneous in both time and space); (2) unclear interactions between social and environmental factors; and (3) uncertainty in climate change modelling and socioeconomic development scenarios. Future risk assessments of climate change will ultimately need to better understand the ecology of RRV disease and to integrate climate change scenarios with local socioeconomic and environmental factors, in order to develop effective adaptation strategies to prevent or reduce RRV transmission. PMID:24612684

  12. Ross Sea

    Atmospheric Science Data Center

    2013-04-16

    article title:  Icebergs in the Ross Sea     View Larger Image Two large icebergs, designated B-15A and C-16, are captured in this Multi-angle Imaging ... the longitudinal quadrant in which it is first seen, and new icebergs sighted in that quadrant are sequentially numbered. B-15 divided from ...

  13. 18. ROSS POWERHOUSE: BUTTERFLY VALVE FROM BELOW AND SCROLL CASE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. ROSS POWERHOUSE: BUTTERFLY VALVE FROM BELOW AND SCROLL CASE DRAIN. TAG INDICATES THE SCROLL CASE DRAIN WAS OPEN, 1989. - Skagit Power Development, Ross Powerhouse, On Skagit River, 10.7 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  14. 20. ROSS POWERHOUSE: BUTTERFLY VALVE AS SEEN FROM INSIDE THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. ROSS POWERHOUSE: BUTTERFLY VALVE AS SEEN FROM INSIDE THE SCROLL CASE, 1987. - Skagit Power Development, Ross Powerhouse, On Skagit River, 10.7 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  15. 5. ROSS POWERHOUSE: SAME CAMERA STATION AS ABOVE PHOTO BUT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. ROSS POWERHOUSE: SAME CAMERA STATION AS ABOVE PHOTO BUT LOOKING EAST. NOTE INFORMATION DISPLAY FOR TOURISTS AT FLOOR LEVEL, 1987. - Skagit Power Development, Ross Powerhouse, On Skagit River, 10.7 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  16. 2. ROSS POWERHOUSE: TRANSFORMER DECK, TAILRACE, AND BOATHOUSE AS SEEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. ROSS POWERHOUSE: TRANSFORMER DECK, TAILRACE, AND BOATHOUSE AS SEEN FROM EAST END OF TRANSFORMER DECK, 1989. - Skagit Power Development, Ross Powerhouse, On Skagit River, 10.7 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  17. Attenuating Mutations in nsP1 Reveal Tissue-Specific Mechanisms for Control of Ross River Virus Infection

    PubMed Central

    Stoermer Burrack, Kristina A.; Hawman, David W.; Jupille, Henri J.; Oko, Lauren; Minor, Marissa; Shives, Katherine D.; Gunn, Bronwyn M.; Long, Kristin M.

    2014-01-01

    ABSTRACT Ross River virus (RRV) is one of a group of mosquito-transmitted alphaviruses that cause debilitating, and often chronic, musculoskeletal disease in humans. Previously, we reported that replacement of the nonstructural protein 1 (nsP1) gene of the mouse-virulent RRV strain T48 with that from the mouse-avirulent strain DC5692 generated a virus that was attenuated in a mouse model of disease. Here we find that the six nsP1 nonsynonymous nucleotide differences between strains T48 and DC5692 are determinants of RRV virulence, and we identify two nonsynonymous nucleotide changes as sufficient for the attenuated phenotype. RRV T48 carrying the six nonsynonymous DC5692 nucleotide differences (RRV-T48-nsP16M) was attenuated in both wild-type and Rag1−/− mice. Despite the attenuated phenotype, RRV T48 and RRV-T48-nsP16M loads in tissues of wild-type and Rag1−/− mice were indistinguishable from 1 to 3 days postinoculation. RRV-T48-nsP16M loads in skeletal muscle tissue, but not in other tissues, decreased dramatically by 5 days postinoculation in both wild-type and Rag1−/− mice, suggesting that the RRV-T48-nsP16M mutant is more sensitive to innate antiviral effectors than RRV T48 in a tissue-specific manner. In vitro, we found that the attenuating mutations in nsP1 conferred enhanced sensitivity to type I interferon. In agreement with these findings, RRV T48 and RRV-T48-nsP16M loads were similar in mice deficient in the type I interferon receptor. Our findings suggest that the type I IFN response controls RRV infection in a tissue-specific manner and that specific amino acid changes in nsP1 are determinants of RRV virulence by regulating the sensitivity of RRV to interferon. IMPORTANCE Arthritogenic alphaviruses, including Ross River virus (RRV), infect humans and cause debilitating pain and inflammation of the musculoskeletal system. In this study, we identified coding changes in the RRV nsP1 gene that control the virulence of RRV and its sensitivity to

  18. Dryland salinity and the ecology of Ross River virus: the ecological underpinnings of the potential for transmission.

    PubMed

    Carver, Scott; Spafford, Helen; Storey, Andrew; Weinstein, Philip

    2009-12-01

    Alterations in transmission of vector-borne zoonoses are often linked to environmental change. However, ecological processes that determine variability in potential for transmission are generally not well understood. Ross River virus (RRV, Togoviridae: Alphavirus) is a mosquito-borne zoonosis in Australia with a significant human disease burden. The inland southwest (Wheatbelt) of Western Australia (WA) is substantially affected by an anthropogenic salinization of agricultural land (dryland salinity). Aedes camptorhynchus Thomson (Diptera: Culicidae) is the dominant vector of RRV in southwest WA and is halophilic. As such, dryland salinity may influence potential for RRV transmission by influencing interactions between Ae. camptorhynchus and mammalian hosts. We surveyed areas of the Wheatbelt with varying salinity impacts and found Ae. camptorhynchus was more abundant in saline areas, whereas sheep Ovis aries (Linnaeus 1758, Bovidae) declined with increasing salinity. We used a deterministic model to examine interactions between Ae. camptorhynchus and mammals, and we assessed potential for RRV transmission. We found variation in potential for RRV transmission was positively related to increasing salinity and abundance of Ae. camptorhynchus and negatively associated with increasing abundance of Macropus fuliginosus (Desmarest 1817, Macropodidae). Abundance of Ae. camptorhynchus determined more variation in potential for RRV transmission than other variables. Accordingly, dryland salinity increases the zoonotic potential for RRV transmission primarily by facilitating abundance of Ae. camptorhynchus. Human RRV notifications do not currently reflect the salinity-RRV transmission potential in the Wheatbelt but appear to be associated with RRV activity in the enzootic coastal zone. We speculate dryland salinity is a determinant of potential for RRV transmission but not activity. Dryland salinity is predicted to expand two- to four-fold by 2050. Preservation and

  19. Genome sequences of a mouse-avirulent and a mouse-virulent strain of Ross River virus.

    PubMed

    Faragher, S G; Meek, A D; Rice, C M; Dalgarno, L

    1988-04-01

    The nucleotide sequence of the genomic RNA of a mouse-avirulent strain of Ross River virus, RRV NB5092 (isolated in 1969), has been determined and the corresponding sequence for the prototype mouse-virulent strain, RRV T48 (isolated in 1959), has been completed. The RRV NB5092 genome is approximately 11,674 nucleotides in length, compared with 11,853 nucleotides for RRV T48. RRV NB5092 and RRV T48 have the same genome organization. For both viruses an untranslated region of 80 nucleotides at the 5' end of the genome is followed by a 7440-nucleotide open reading frame which is interrupted after 5586 nucleotides by a single opal termination codon. By homology with other alphaviruses, the 5586-nucleotide open reading frame encodes the nonstructural proteins nsP1, nsP2, and nsP3; a fourth nonstructural protein, nsP4, is produced by read-through of the opal codon. The RRV nonstructural proteins show strong homology with the corresponding proteins of Sindbis virus and Semliki Forest virus in terms of size, net charge, and hydropathy characteristics. However, homology is not uniform between or within the proteins; nsP1, nsP2, and nsP4 contain extended domains which are highly conserved between alphaviruses, while the C-terminal region of nsP3 shows little conservation in sequence or length between alphaviruses. An untranslated "junction" region of 44 nucleotides (for RRV NB5092) or 47 nucleotides (for RRV T48) separates the nonstructural and structural protein coding regions. The structural proteins (capsid-E3-E2-6K-E1) are translated from an open reading frame of 3762 nucleotides which is followed by a 3'-untranslated region of approximately 348 nucleotides (for RRV NB5092) or 524 nucleotides (for RRV T48). Excluding deletions and insertions, the genomes of RRV NB5092 and RRV T48 differ at 284 nucleotides, representing a sequence divergence of 2.38%. Sequence deletions or insertions were found only in the noncoding regions and include a 173-nucleotide deletion in the 3

  20. Ross River virus risk associated with dispersal of Aedes (Ochlerotatus) camptorhynchus (Thomson) from breeding habitat into surrounding residential areas: muddy lakes, Western Australia.

    PubMed

    Jardine, Andrew; Neville, Peter J; Dent, Colin; Webster, Carla; Lindsay, Michael D A

    2014-07-01

    Rapid population growth in Western Australia has resulted in increased development of land for residential housing, and new developments are often proposed close to water because of intrinsic aesthetic values. However, this placement may place future residents at risk of mosquito-borne disease, of which Ross River virus (RRV) disease is the most common in Australia. Mosquito dispersal data were combined with a spatial analysis of human RRV cases to show that mosquitoes dispersed readily from larval habitat into surrounding low- and high-density residential areas and that residents living within 2 km of mosquito breeding habitat had a significantly higher rate of RRV disease. This finding highlights the importance of planning authorities in state and local governments to consider the implications of mosquito-borne disease risks when assessing residential development applications. PMID:24799370

  1. Regulation of type I-interferon responses in the human epidermal melanocyte cell line SKMEL infected by the Ross River alphavirus.

    PubMed

    Assi, Mohamad; Thon-Hon, Vincent Gérard; Jaffar-Bandjee, Marie-Christine; Martinez, Audrey; Gasque, Philippe

    2015-12-01

    Melanocytes are melanin-producing cells and with emerging innate immune functions including the expression of antiviral interferon-type I cytokines. We herein ascertained the susceptibility of the human melanocytes to Ross River alphavirus (RRV) infection and analyzed the subsequent immune responses. We demonstrated for the first time that (1) SKMEL-28 melanocyte cell line was susceptible to RRV infection and displaying major cytopathic activities and (2) RRV interfered with the interferon-type I response by altering nuclear translocation of pSTAT1 and pSTAT2 in infected SKMEL-28. These results suggest that the human melanoma cell line SKMEL-28 is a valuable model to analyze the mechanisms involved in severe skin manifestations and melanocyte's immunity at the portal of entry of major infection by arboviruses. PMID:26159111

  2. A Tyrosine-to-Histidine Switch at Position 18 of the Ross River Virus E2 Glycoprotein Is a Determinant of Virus Fitness in Disparate Hosts

    PubMed Central

    Jupille, Henri J.; Medina-Rivera, Melisa; Hawman, David W.; Oko, Lauren

    2013-01-01

    Arthritogenic alphaviruses are human pathogens maintained in nature through alternating replication in vertebrates and mosquitoes. Using chimeric viruses, we previously reported that replacement of the PE2 coding region of the T48 strain of Ross River virus (RRV-T48) with that from the attenuated DC5692 strain, which differ by 7 amino acids, resulted in an attenuated disease phenotype in a mouse model of RRV-induced rheumatic disease. Here, we demonstrate that introduction of one of these amino acid differences, a tyrosine (Y)-to-histidine (H) change at position 18 of the E2 glycoprotein (E2 Y18H), into the RRV-T48 genetic background was sufficient to generate a virus that caused dramatically less severe musculoskeletal disease in mice. The attenuated phenotype of RRV-T48 E2 Y18H was associated with reduced viral loads in musculoskeletal tissues, reduced viremia, and less efficient virus spread. Consistent with these findings, RRV-T48 E2 Y18H replicated less well in mammalian cells in vitro due to significantly reduced PFU released per infected cell. In contrast, RRV-T48 E2 Y18H replicated more efficiently than RRV-T48 in C6/36 mosquito cells. Competition studies confirmed that RRV-T48 E2 Y18H had a fitness advantage in mosquito cells and a fitness disadvantage in mammalian cells. Interestingly, all sequenced Ross River viruses encode either a tyrosine or a histidine at E2 position 18, and this holds true for other alphaviruses in the Semliki Forest antigenic complex. Taken together, these findings suggest that a tyrosine-to-histidine switch at E2 position 18 functions as a regulator of RRV fitness in vertebrate and invertebrate cells. PMID:23514884

  3. Development of a SYBR green I-based quantitative RT-PCR for Ross River virus: Application in vector competence studies and antiviral drug evaluation.

    PubMed

    Dash, Paban Kumar; Agarwal, Ankita; Sharma, Shashi; Saha, Amrita; Joshi, Gaurav; Gopalan, Natarajan; Sukumaran, Devanathan; Parida, Man Mohan

    2016-08-01

    Ross River virus (RRV) is an emerging Alphavirus and is presently endemic in many parts of Oceania. Keeping in mind its emergence, we developed a molecular detection system and utilized it to study vector competence and evaluate activity of antiviral compounds against RRV. A SYBR Green I-based quantitative RT-PCR for detection of RRV was developed targeting the E2 gene, with a detection limit of 100 RNA copies/reaction. The specificity was confirmed with closely related Alphaviruses and Flaviviruses. The assay was applied to study the vector competence of Indian Aedes aegypti for RRV, which revealed 100% infection and dissemination rate with 75% transmission rate. Viral RNA was found in saliva as early as 3day post infection (dpi). Further application of the assay in antiviral drug evaluation revealed the superior in vitro activity of ribavirin compared to chloroquine in Vero cells. Successful demonstration of this assay to detect RRV in low titre mosquito samples makes it a sensitive tool in vector surveillance. This study also showed that Indian Ae. aegypti are well competent to transmit RRV highlighting the risk of its introduction to naïve territories across continents. Further validation of this assay, revealed its utility in screening of potential antivirals against RRV. PMID:27105737

  4. 17. ROSS POWERHOUSE: BUTTERFLY VALVE CONTROLS FOR UNIT 43. THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. ROSS POWERHOUSE: BUTTERFLY VALVE CONTROLS FOR UNIT 43. THE BUTTERFLY VALVE LOCK INDICATES THE BUTTERFLY VALVE IS CLOSED AS UNIT 43 WAS SHUT DOWN FOR REPAIRS, 1989. - Skagit Power Development, Ross Powerhouse, On Skagit River, 10.7 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  5. An inactivated Ross River virus vaccine is well tolerated and immunogenic in an adult population in a randomized phase 3 trial.

    PubMed

    Wressnigg, Nina; van der Velden, Maikel V W; Portsmouth, Daniel; Draxler, Wolfgang; O'Rourke, Maria; Richmond, Peter; Hall, Stephen; McBride, William J H; Redfern, Andrew; Aaskov, John; Barrett, P Noel; Aichinger, Gerald

    2015-03-01

    Ross River virus (RRV) is endemic in Australia and several South Pacific Islands. More than 90,000 cases of RRV disease, which is characterized by debilitating polyarthritis, were reported in Australia in the last 20 years. There is no vaccine available to prevent RRV disease. A phase 3 study was undertaken at 17 sites in Australia to investigate the safety and immunogenicity of an inactivated whole-virus Vero cell culture-derived RRV vaccine in 1,755 healthy younger adults aged 16 to 59 years and 209 healthy older adults aged ≥60 years. Participants received a 2.5-μg dose of Al(OH)(3)-adjuvanted RRV vaccine, with a second and third dose after 3 weeks and 6 months, respectively. Vaccine-induced RRV-specific neutralizing and total IgG antibody titers were measured after each immunization. Vaccine safety was monitored over the entire study period. The vaccine was safe and well-tolerated after each vaccination. No cases of arthritis resembling RRV disease were reported. The most frequently reported systemic reactions were headache, fatigue, and malaise; the most frequently reported injection site reactions were tenderness and pain. After the third immunization, 91.5% of the younger age group and 76.0% of the older age group achieved neutralizing antibody titers of ≥1:10; 89.1% of the younger age group and 70.9% of the older age group achieved enzyme-linked immunosorbent assay (ELISA) titers of ≥11 PanBio units. A whole-virus Vero cell culture-derived RRV vaccine is well tolerated in an adult population and induces antibody titers associated with protection from RRV disease in the majority of individuals. (This study is registered at www.clinicaltrials.gov under registration no. NCT01242670.). PMID:25540268

  6. Ross Ice Shelf

    Atmospheric Science Data Center

    2013-04-16

    ... funded by the National Science Foundation, several penguin colonies near the Ross Ice Shelf, Antarctica have not been able to ... affected include one of Antarctica's most populous Adelie penguin colonies, as well as a small colony of Emperor penguins. These ...

  7. Victoria Land, Ross Sea, and Ross Ice Shelf, Antarctica

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On December 19, 2001, MODIS acquired data that produced this image of Antarctica's Victoria Land, Ross Ice Shelf, and the Ross Sea. The coastline that runs up and down along the left side of the image denotes where Victoria Land (left) meets the Ross Ice Shelf (right). The Ross Ice Shelf is the world's largest floating body of ice, approximately the same size as France. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  8. 78 FR 38298 - Ross Stores, Inc. et al., Provisional Acceptance of a Settlement Agreement and Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-26

    .... 1118.20, Ross Stores, Inc., Ross Procurement, Inc., Ross Merchandising, Inc., and Ross Dress for Less... Ross, including Ross Stores, Inc., Ross Procurement, Inc., Ross Merchandising, Inc., and Ross Dress for... Stores, Inc., Ross Procurement, Inc., Ross Merchandising, Inc. and Ross Dress for Less (Ross), and the...

  9. Valine Nutrient Recommendations for Ross × Ross 308 Broilers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Studies delineating dietary Val needs of modern commercial broilers are sparse. Three studies were conducted to determine the dietary Val nutrient minimum of Ross × Ross 308 male broilers. Three time periods were evaluated independently, 0 to 14 d (starter), 14 to 28 d (grower) and 28 to 42 d (finis...

  10. Bandura, Ross, and Ross: Observational Learning and the Bobo Doll

    ERIC Educational Resources Information Center

    Artino, Anthony R., Jr.

    2007-01-01

    Since the publication of their seminal article entitled, "Transmission of Aggression Through Imitation of Aggressive Models" (Bandura, Ross, & Ross, 1961), the work of Albert Bandura and his co-authors has had an immeasurable impact on the field of psychology, in general, and educational psychology, more specifically. The purpose of this report is…

  11. Ross ice shelf vibrations

    NASA Astrophysics Data System (ADS)

    Bromirski, P. D.; Diez, A.; Gerstoft, P.; Stephen, R. A.; Bolmer, T.; Wiens, D. A.; Aster, R. C.; Nyblade, A.

    2015-09-01

    Broadband seismic stations were deployed across the Ross Ice Shelf (RIS) in November 2014 to study ocean gravity wave-induced vibrations. Initial data from three stations 100 km from the RIS front and within 10 km of each other show both dispersed infragravity (IG) wave and ocean swell-generated signals resulting from waves that originate in the North Pacific. Spectral levels from 0.001 to 10 Hz have the highest accelerations in the IG band (0.0025-0.03 Hz). Polarization analyses indicate complex frequency-dependent particle motions, with energy in several frequency bands having distinctly different propagation characteristics. The dominant IG band signals exhibit predominantly horizontal propagation from the north. Particle motion analyses indicate retrograde elliptical particle motions in the IG band, consistent with these signals propagating as Rayleigh-Lamb (flexural) waves in the ice shelf/water cavity system that are excited by ocean wave interactions nearer the shelf front.

  12. Chikungunya Virus Glycoproteins Pseudotype with Lentiviral Vectors and Reveal a Broad Spectrum of Cellular Tropism

    PubMed Central

    Wang, Hua; Liu, Shuangchun; Yu, Lianhua; Sun, Lingfen; Qu, Ying

    2014-01-01

    Background Outbreaks of the Chikungunya virus (CHIKV) infection has been documented in over 40 countries, resulting in clinical symptoms characterized by fever and joint pain. Diagnosing CHIKV in a clinical lab setting is often omitted because of the high lab safety requirement. An infection system that mimics CHIKV infection will permit clinical evaluation of the production of neutralizing antibody for both disease diagnostics and treatment. Methodology/Principal Findings We generated a CHIKV construct expressing CHIKV structural proteins. This construct permits the production of CHIKV pseudo-viral particles with a luciferase reporter. The pseudo-virus was able to infect a wide range of cell lines. The pseudovirus could be neutralized by the addition of neutralizing antibodies from patients. Conclusions Taken together, we have developed a powerful system that can be handled at biosafety level 2 laboratories for evaluation of existence of CHIKV neutralizing antibodies. PMID:25333782

  13. Resting lymphocyte transduction with measles virus glycoprotein pseudotyped lentiviral vectors relies on CD46 and SLAM

    SciTech Connect

    Zhou Qi; Schneider, Irene C.; Gallet, Manuela; Kneissl, Sabrina; Buchholz, Christian J.

    2011-05-10

    The measles virus (MV) glycoproteins hemagglutinin (H) and fusion (F) were recently shown to mediate transduction of resting lymphocytes by lentiviral vectors. MV vaccine strains use CD46 or signaling lymphocyte activation molecule (SLAM) as receptor for cell entry. A panel of H protein mutants derived from vaccine strain or wild-type MVs that lost or gained CD46 or SLAM receptor usage were investigated for their ability to mediate gene transfer into unstimulated T lymphocytes. The results demonstrate that CD46 is sufficient for efficient vector particle association with unstimulated lymphocytes. For stable gene transfer into these cells, however, both MV receptors were found to be essential.

  14. The South Pole and the Ross Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image shows a rare clear view of the South Pole (lower right) and the Ross Sea, Antarctica. The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) acquired the scene on December 26, 2001. The geographic South Pole is located in the center of Antarctica, at an altitude of 2,900 meters (9,300 feet). It rests on a continent-wide ice sheet that is 2,870 m thick, with the underlying bedrock only 30 m (98 feet) above sea level. The ice underlying the South Pole is as much as 140,000 years old, and is currently accumulating at about 82 cm (32 inches) per year. Roughly 2,500 km (1,550 miles) away is the green water of the Ross Sea, which indicates the presence of large numbers of phytoplankton. This is a highly productive part of the world's oceans. Also note the ice gathered around McMurdo Sound, seen toward the lefthand shoreline of the Ross Sea, at the edge of the Ross Ice Shelf. According to National Science Foundation researchers, this ice is making it difficult for penguins to reach their food supply. Separating the continental Antarctic ice sheet from the Ross Sea are the Queen Maud Mountains and the Ross Ice Shelf. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  15. Icebergs in the Ross Sea, Antarctica

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Two large icebergs, designated B-15A and C-16, are captured in this MISR nadir camera view of the Ross Ice Shelf and Ross Sea in Antarctica. The image was acquired on December 10, 2000 during Terra orbit 5220.

    Iceberg C-16 calved off the ice shelf in late September and is nearly 50 kilometers in length. It is seen here having migrated to the vicinity of Cape Bird on Ross Island. The initial letter designation in an iceberg's name denotes the longitudinal quadrant in which it is first seen, and new icebergs sighted in that quadrant are sequentially numbered. B-15 divided from the ice shelf last March, and initially was nearly as large as the state of Connecticut. It has since broken up into several pieces, hence the final letter designation in the berg shown in this image.

    Ross Island lies between 77 and 78 degrees south latitude, and consists of several volcanic peaks, of which the still active Mt. Erebus is the tallest (3794 meters). It overlooks McMurdo Station, a U.S. research facility located near the tip of the island's Hut Point Peninsula.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

  16. Sedimentary basins in Ross Sea, Antarctica

    SciTech Connect

    Cooper, A.K.; Davey, F.J.

    1986-07-01

    The Ross Sea lies in the Pacific sector of the Antarctic continental margin. Three major sedimentary basins (from east to west, the Eastern, Central, and Victoria Land basins) lie beneath the broad, deep continental shelf of the Ross Sea. These north-south-trending basins occur in the extensionally deformed region between East and West Antarctica. Multichannel seismic reflection (MCS) surveys have been conducted over these basins since 1980 by West German, French, Japanese, and US expeditions. The MCS and previous geophysical surveys have shown that the three basins contain 5-6 km of sedimentary rock, possibly Late Cretaceous and younger. An additional 6-8 km of sedimentary and volcanic rock lies within the deeper parts of the Victoria Land basin. The basins are separated by uplifted and eroded basement ridges covered by thin sedimentary sections. Each basin has distinct characteristics, commonly related to its extensional origin. Petroleum hydrocarbons are unknown from the Ross Sea region, with the possible exception of ethane gas recovered by the Deep Sea Drilling Project. Previous model studies, based on estimated sediment thickness, assumed temperature gradients, and postulated seismostratigraphy, indicate that hydrocarbons could be generated at depths of 3.5-6km within the sedimentary section. However, this hypothesis cannot be verified without further geologic and geophysical data from the Ross Sea region.

  17. Climatological aspects of mesoscale cyclogenesis over the Ross Sea and Ross Ice shelf regions of Antarctica

    SciTech Connect

    Carrasco, J.F.; Bromwich, D.H.

    1994-11-01

    A one-year (1988) statistical study of mesoscale cyclogenesis near Terra Nova Bay and Byrd Glacier, Antarctica, was conducted using high-resolution digital satellite imagery and automatic weather station data. Results indicate that on average two (one) mesoscale cyclones form near Terra Nova Bay (Byrd Glacier) each week, confirming these two locations as mesoscale cyclogeneis areas. The maximum (minimum) weekly frequency of mesoscale cyclones occurred during the summer (winter). The satellite survey of mesoscale vortices was extended over the Ross Sea and Ross Ice Shelf. Results suggest southern Marie Byrd Land as another area of mesoscale cyclone formation. Also, frequent mesoscale cyclonic activity was noted over the Ross Sea and Ross Ice Shelf, where, on average, six and three mesoscale vortices were observed each week, respectively, with maximum (minimum) frequency during summer (winter) in both regions. The majority (70-80%) of the vortices were of comma-cloud type and were shallow. Only around 10% of the vortices near Terra Nova Bay and Byrd Glacier were classified as deep vortices, while over the Ross Sea and Ross Ice Shelf around 20% were found to be deep. The average large-scale pattern associated with cyclogenesis days near Terra Nova Bay suggests a slight decrease in the sea level pressure and 500-hPa geopotential height to the northwest of this area with respect to the annual average. This may be an indication of the average position of synoptic-scale cyclones entering the Ross Sea region. Comparison with a similar study but for 1984-85 shows that the overall mesoscale cyclogenesis activity was similar during the three years, but 1985 was found to be the year with greater occurrence of {open_quotes}significant{close_quotes} mesoscales cyclones. The large-scale pattern indicates that this greater activity is related to a deeper circumpolar trough and 500-hPa polar vortex for 1985 in comparison to 1984 and 1988. 64 refs., 13 figs., 5 tabs.

  18. Iceberg B-15, Ross Ice Shelf, Antarctica

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Iceberg B-15 broke from the Ross Ice Shelf in Antarctica in late March. Among the largest ever observed, the new iceberg is approximately 170 miles long x 25 miles wide. Its 4,250 square-mile area is nearly as large as the state of Connecticut. The iceberg was formed from glacial ice moving off the Antarctic continent and calved along pre-existing cracks in the Ross Ice Shelf near Roosevelt Island. The calving of the iceberg essentially moves the northern boundary of the ice shelf about 25 miles to the south, a loss that would normally take the ice shelf as long as 50-100 years to replace. This infrared image was acquired by the DMSP (Defense Meteorological Satellite Program) F-13 satellite on April 13, 2000. For more images see Antarctic Meteorological Research Center Image courtesy of the University of Wisconsin - Madison, Space Science and Engineering Center, Antarctic Meteorological Research Center

  19. 1989 Bowen Award to Ross Taylor

    NASA Astrophysics Data System (ADS)

    Burke, Kevin

    Ross Taylor graduated with a B.Sc. degree from Canterbury College of the then University of New Zealand in 1948 and an M.Sci in 1951. He followed the footsteps of Ernest Rutherford and other distinguished New Zealanders (including a surprisingly large number of AGU Fellows in proportion to the small population of New Zealand) by going aboard to further pursue his scientific education.

  20. Phenolic compounds in Ross Sea water

    NASA Astrophysics Data System (ADS)

    Zangrando, Roberta; Barbaro, Elena; Gambaro, Andrea; Barbante, Carlo; Corami, Fabiana; Kehrwald, Natalie; Capodaglio, Gabriele

    2016-04-01

    Phenolic compounds are semi-volatile organic compounds produced during biomass burning and lignin degradation in water. In atmospheric and paleoclimatic ice cores studies, these compounds are used as biomarkers of wood combustion and supply information on the type of combusted biomass. Phenolic compounds are therefore indicators of paleoclimatic interest. Recent studies of Antarctic aerosols highlighted that phenolic compounds in Antarctica are not exclusively attributable to biomass burning but also derive from marine sources. In order to study the marine contribution to aerosols we developed an analytical method to determine the concentration of vanillic acid, vanillin, p-coumaric acid, syringic acid, isovanillic acid, homovanillic acid, syringaldehyde, acetosyringone and acetovanillone present in dissolved and particle phases in Sea Ross waters using HPLC-MS/MS. The analytical method was validated and used to quantify phenolic compounds in 28 sea water samples collected during a 2012 Ross Sea R/V cruise. The observed compounds were vanillic acid, vanillin, acetovanillone and p-coumaric acid with concentrations in the ng/L range. Higher concentrations of analytes were present in the dissolved phase than in the particle phase. Sample concentrations were greatest in the coastal, surficial and less saline Ross Sea waters near Victoria Land.

  1. Rabies virus glycoprotein pseudotyping of lentiviral vectors enables retrograde axonal transport and access to the nervous system after peripheral delivery.

    PubMed

    Mazarakis, N D; Azzouz, M; Rohll, J B; Ellard, F M; Wilkes, F J; Olsen, A L; Carter, E E; Barber, R D; Baban, D F; Kingsman, S M; Kingsman, A J; O'Malley, K; Mitrophanous, K A

    2001-09-15

    In this report it is demonstrated for the first time that rabies-G envelope of the rabies virus is sufficient to confer retrograde axonal transport to a heterologous virus/vector. After delivery of rabies-G pseudotyped equine infectious anaemia virus (EIAV) based vectors encoding a marker gene to the rat striatum, neurons in regions distal from but projecting to the injection site, such as the dopaminergic neurons of the substantia nigra pars compacta, become transduced. This retrograde transport to appropriate distal neurons was also demonstrated after delivery to substantia nigra, hippocampus and spinal cord and did not occur when vesicular stomatitis virus glycoprotein (VSV-G) pseudotyped vectors were delivered to these sites. In addition, peripheral administration of rabies-G pseudotyped vectors to the rat gastrocnemius muscle leads to gene transfer in motoneurons of lumbar spinal cord. In contrast the same vector pseudotyped with VSV-G transduced muscle cells surrounding the injection site, but did not result in expression in any cells in the spinal cord. Long-term expression was observed after gene transfer in the nervous system and a minimal immune response which, together with the possibility of non-invasive administration, greatly extends the utility of lentiviral vectors for gene therapy of human neurological disease. PMID:11590128

  2. Rabies-virus-glycoprotein-pseudotyped recombinant baculovirus vaccine confers complete protection against lethal rabies virus challenge in a mouse model.

    PubMed

    Wu, Qunfeng; Yu, Fulai; Xu, Jinfang; Li, Yang; Chen, Huanchun; Xiao, Shaobo; Fu, Zhen F; Fang, Liurong

    2014-06-25

    Rabies virus has been an ongoing threat to humans and animals. Here, we developed a new strategy to generate a rabies virus vaccine based on a pseudotyped baculovirus. The recombinant baculovirus (BV-RVG/RVG) was pseudotyped with the rabies virus glycoprotein (RVG) and also simultaneously expressed another RVG under the control of the immediate early CMV promoter. In vitro, this RVG-pseudotyped baculovirus vector induced syncytium formation in insect cells and displayed more efficient gene delivery into mammalian cells. Mice immunized with BV-RVG/RVG developed higher levels of virus-neutralizing antibodies, and conferred 100% protection against rabies viral challenge. These data indicate that the RVG-pseudotyped baculovirus BV-RVG/RVG can be used as an alternative strategy to develop a safe and efficacious vaccine against the rabies virus. PMID:24793501

  3. Results of geophysical research in Ross Sea

    SciTech Connect

    Hinz, K.

    1987-05-01

    The Ross Sea is underlain from the east to the west by three north-south-trending sedimentary basins: the Eastern basin (east of the 180/sup 0/ meridian), the Central basin (along 175/sup 0/), and the Victoria Land basin. In the center of the Eastern basin, the thickness of the sediments generally ranges between 3000 and 6000 m. The pre-late Oligocene sediments occur only in the center of the basin. There are no indications of block faulting in the sedimentary sequence, indicating that synsedimentary subsidence has been the dominant tectonic process. A broad basement high, the Central High, lies to the west of the Eastern basin. The top of basement is a peneplain over large parts of the high. The overlying sediments are mostly younger than Oligocene. The Central basin lies to the west of the Central High, extends approximately north-south through the central Ross Sea. Sedimentary thicknesses in excess of 6000 m were observed. A relatively narrow basement high, trending north-south, separates the Central basin from the complex Victoria Land basin. The Victoria Land basin is a 150-km wide basin that extends from the Ross Ice shelf to 75/sup 0/S. It is bounded to the north by a shallow and characteristically planated basement high, the Coulman High, and to the west by the uplifted Transantarctic Mountains. The Victoria Land basin is subdivided by north-south-trending zones of volcanic/magmatic intrusions, probably equivalents of the Neogene Hallett Volcanics and McMurdo Volcanics, respectively, that affected the Victoria Land basin, resulting in uplift and inversion of parts of the basin.

  4. Paul de Kruif's Microbe Hunters and an outraged Ronald Ross.

    PubMed

    Chernin, E

    1988-01-01

    Paul de Kruif's book, Microbe Hunters, published in New York in 1926, was a romanticized medical "history," written in a breathless style, that describes the lives and works of a dozen famous figures, ranging from Leeuwenhoek to Sir Ronald Ross. Ross, who received the Nobel Prize in 1902 for his discovery that certain mosquitoes transmit malaria, resented de Kruif's personal remarks and his version of the malaria story, especially concerning the disputes with Italian workers over priorities. In a little-known polemic "review" of Microbe Hunters, Ross castigated de Kruif for statements he considered libelous. While Ross could not sue for libel across the Atlantic, his threatened action for libel forced the publisher of the British edition of Microbe Hunters to delete the chapter about Ross and one about David Bruce, Ross's countryman. de Kruif's book, a best-seller in its day and influential among the young for a generation, now seems gauche and anachronistic. While Ross seems to have been justified in some of his complaints about Microbe Hunters, the bitter tone of his reactions all but confirms de Kruif's opinion of him. Ross died in 1932 with a permanent niche in medical history; de Kruif died in 1971 and is little remembered except, perhaps, for Microbe Hunters. PMID:3293166

  5. 27 CFR 9.221 - Fort Ross-Seaview.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... point is on the Arched Rock map at the intersection of the 920-foot elevation line and Meyers Grade Road, T8N, R12W. From the beginning point, proceed northwest on Meyers Grade Road approximately 4.3 miles, on to the Fort Ross map, to the intersection of Meyers Grade Road with Seaview and Fort Ross...

  6. 27 CFR 9.221 - Fort Ross-Seaview.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... point is on the Arched Rock map at the intersection of the 920-foot elevation line and Meyers Grade Road, T8N, R12W. From the beginning point, proceed northwest on Meyers Grade Road approximately 4.3 miles, on to the Fort Ross map, to the intersection of Meyers Grade Road with Seaview and Fort Ross...

  7. 27 CFR 9.221 - Fort Ross-Seaview.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... point is on the Arched Rock map at the intersection of the 920-foot elevation line and Meyers Grade Road, T8N, R12W. From the beginning point, proceed northwest on Meyers Grade Road approximately 4.3 miles, on to the Fort Ross map, to the intersection of Meyers Grade Road with Seaview and Fort Ross...

  8. Relationships in Areal Variability: The Ross Sea Polynya and Ice

    NASA Astrophysics Data System (ADS)

    Ward, Jason Michael

    General increases in Antarctic sea ice coverage occur primarily in the Ross Sea. This study investigates the Ross Sea Polynya's relationship with the Ross Sea ice areal coverage. A unique, relatively long term Ross Sea Polynya area dataset was created through the application of the Polynya Signature Simulation Method (PSSM) onto Special Sensor Microwave Imager (SSM/I) data inputs. Bivariate regression analyses were used to determine the relationships, at the 95% confidence level, between Ross Sea Polynya and ice areal trends, annual seasonalities, and anomalies at the full temporal scale as well as the monthly level. Polynya and sea ice have significant positive relationships in the late austral summer and early spring (February to March), and a significant negative relationship in the late austral winter (August). The areal anomalies only had a significant relationship in February, while the trends were not correlated at any time.

  9. Seismic Stratigraphy Of The Ross Island Flexural Moat Under Western Mcmurdo-Ross Ice Shelf, Antarctica

    NASA Astrophysics Data System (ADS)

    Horgan, H.; Naish, T.; Bannister, S.; Balfour, N.; Wilson, G.; Finnemore, F.

    2003-04-01

    Ross Island is a volcanic complex that began forming with the emplacement Mount Bird around 5 million years ago, though it has developed most significantly within the last 1 million years with the emplacement of the c. 4km high Mount Erebus. Throughout this time, loading of the lithosphere by this volcanic complex has warped the underlying crust into a subcircular submarine depression that has been accumulating sediment in series of flexural moat basins around the periphery of the island. Due to the depth of the floor of the depression (800-1000 m below sea level today), the sediment fill has largely escaped subsequent erosion by grounded ice of the McMurdo and Ross Ice Shelves (MRIS) and Ross Ice Sheet. Our interest is in the 1.5 km-thick sedimentary record that now lies beneath the deepest part of the depression and is covered by the MRIS. The sediments here have the potential to provide a continuous and high resolution (10^2-10^3 year) record back to 5 million years of the past behaviour of the MRIS and its influence on bottom water production in Ross Sea. The flexural moat basin-fill between the volcanic complexes of Ross and White Islands, which because of its remoteness is only now being investigated for the first time, is in a key location beneath the north western corner of the Ross Ice Shelf (RIS) where it flows into the McMurdo Ice Shelf (MIS). This site forms one of the 4 objectives of the ANDRILL Programme and is scheduled for drilling in 2005. Here we present new multi-channel seismic reflection data from over-ice shelf surveys conducted between 2001-2003, that elucidate the geometry and stratigraphy of the flexural-moat basin-fill and its relationship to the adjacent volcanics. We illustrate the proposed drill sites and make an initial prognosis of the sedimentary fill. The uppermost c. 500 m of the sedimentary succession is expected to be fine-grained muds with occasional glacigene sediment and layers of volcanic ash. Underlying strata may become

  10. Expanding indications for the Ross operation.

    PubMed

    Joyce, F; Tingleff, J; Pettersson, G

    1995-07-01

    During the past 2.5 years, 50 Ross operations have been performed at Rigshospitalet in Copenhagen in a broad range of patients with aortic valve disease including children and adults from 6 weeks to 71 years of age. Many patients had complicating conditions including endocarditis (n = 13, eight native, five prosthetic valve), prosthetic valve dysfunction (n = 4), subvalvular obstruction (n = 3) treated by septal myectomy (n = 1) or modified Konno operation (n = 2), ascending aortic aneurysm (n = 2), ventricular septum defect (n = 1), mitral valve disease (n = 6), rheumatic heart disease (n = 4), coronary artery disease (n = 1), and extreme obesity (n = 1). All operations were performed as free-standing total aortic root replacements. The results have been encouraging with low mortality (2%) and no major morbidity. One patient has been reoperated because of autograft insufficiency due to left coronary cusp prolapse and two additional patients have grade 2 autograft insufficiency and are being followed closely. Two patients have developed early pulmonary homograft stenosis, which has required pulmonary homograft replacement. Despite these problems, we are enthusiastic about this operation and believe it may emerge as operation of choice for most patients under 60-65 years of age with aortic valve disease and for patients with prosthetic or advanced native aortic valve endocarditis. With increasing frequency, our choice has been to proceed with a Ross operation, and currently, our only absolute contraindication is Marfan's syndrome. Based on reported recurrent disease in patients with rheumatic valve disease, the autograft should be used with caution for this indication.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7582141

  11. The Paediatric Cardiology Hall of Fame – Donald Nixon Ross.

    PubMed

    Somerville, Jane

    2015-10-01

    Donald Nixon Ross, FRCS (4 October 1922 to 7 July 2014) was a South African-born British cardiothoracic surgeon, who developed the pulmonary autograft, known as the Ross procedure, for the treatment of aortic valve disease, and also performed the first heart transplant in the United Kingdom in 1968. This paper, written by Jane Somerville, Professor of Cardiology [Retired], Imperial College London, London, United Kingdom, provides the personal recollections about Donald Ross from Jane Somerville, and thus provides a unique snapshot of cardiac surgical history. PMID:26574617

  12. Seismic Stratigraphy of the Ross Island Flexural Basin, West Antarctica

    NASA Astrophysics Data System (ADS)

    Wenman, C. P.; Harry, D. L.; Jha, S.

    2014-12-01

    Marine seismic reflection data collected over the past 30+ years in the Ross Sea region of southwest Antarctica has been tied to the ANDRILL and CIROS boreholes to develop a seismic stratigraphic model that constrains the spatial and temporal evolution of the flexural basin surrounding Ross Island. Ross Island was formed from 4.6 Ma to present by extrusive volcanism in the Ross Sea at the southern end of the Terror Rift. Preliminary mapping has identified a hinge zone trending northeastward from Mt. Bird, separating the well-developed flexural moat on the west side of the island from sub-horizontal strata on the northeast and east sides. The flexural moat on the west and north-northwest sides of the island is approximately 40-45 km wide with sediment fill thickness of roughly 1100 m. Seismic lines to the east and northeast of the island do not indicate the presence of a flexural moat. Instead, the thickness of strata on the east side of the island that are time-equivalent to the infill of the flexural moat on the west side remains constant from the Coulman High westward to within ~28 km of Ross Island (the landward extent of the seismic data coverage). The concordant post-Miocene strata on the east and northeast sides of Ross Island imply either that the flexural basin does not extend more than ~28 km eastward from the Ross Island shoreline, or that the flexural basin is not present on that side of the island. The first scenario requires that the elastic strength of the lithosphere differ on either side of the hinge. The second scenario can be explained by a mechanical rupture in the lithosphere beneath Ross Island, with Ross Island acting as an end-load on a mechanical half-plate that forms the lithosphere beneath Ross Island and westward. In this model, the lithosphere east of Ross Island and the hinge forms a second half-plate, bearing little or none of the Ross Island volcanic load.

  13. 33 CFR 117.949 - Tennessee River.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Tennessee River. 117.949 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Tennessee § 117.949 Tennessee River. The draws of the Chief John Ross Bridge over the Tennessee River, mile 464.1, at Chattanooga, and the Southern...

  14. 33 CFR 117.949 - Tennessee River.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Tennessee River. 117.949 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Tennessee § 117.949 Tennessee River. The draws of the Chief John Ross Bridge over the Tennessee River, mile 464.1, at Chattanooga, and the Southern...

  15. 33 CFR 117.949 - Tennessee River.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Tennessee River. 117.949 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Tennessee § 117.949 Tennessee River. The draws of the Chief John Ross Bridge over the Tennessee River, mile 464.1, at Chattanooga, and the Southern...

  16. 33 CFR 117.949 - Tennessee River.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Tennessee River. 117.949 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Tennessee § 117.949 Tennessee River. The draws of the Chief John Ross Bridge over the Tennessee River, mile 464.1, at Chattanooga, and the Southern...

  17. ROSS Skills, Knowledge, and Abilities Training Evaluation. Gaps and Recommendations

    SciTech Connect

    Ala, Maureen; Gruidl, Jeremiah; Buddemeier, Brooke

    2015-09-30

    This document describes the development of the ROSS SKAs, the cross-mapping of the SKAs to the available training, identifies gaps in the SKA and training, and provides recommendations to address those gaps.

  18. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area... the U.S./Canadian border to the end of the road at East Landing. (3) Access and circulatory roads...

  19. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area... the U.S./Canadian border to the end of the road at East Landing. (3) Access and circulatory roads...

  20. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area... the U.S./Canadian border to the end of the road at East Landing. (3) Access and circulatory roads...

  1. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area... the U.S./Canadian border to the end of the road at East Landing. (3) Access and circulatory roads...

  2. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area... the U.S./Canadian border to the end of the road at East Landing. (3) Access and circulatory roads...

  3. Circulation and melting beneath the ross ice shelf.

    PubMed

    Jacobs, S S; Gordon, A L; Ardai, J L

    1979-02-01

    Thermohaline observations in the water column beneath the Ross Ice Shelf and along its terminal face show significant vertical stratification, active horizontal circulation, and net melting at the ice shelf base. Heat is supplied by seawater that moves southward beneath the ice shelf from a central warm core and from a western region of high salinity. The near-freezing Ice Shelf Water produced flows northward into the Ross Sea. PMID:17734137

  4. A study on the polynyas of the Ross Sea

    NASA Astrophysics Data System (ADS)

    Flocco, D.; Biggs, N. R. T.; Zambianchi, E.; Wadhams, P.

    2003-04-01

    The Ross Sea polynya is a complex oceanographic feature with a strong influence on the heat balances of the Ross Sea. The opening of the Ross Sea polynya depends on three main factors: the katabatic surges associated with the cyclogenesys events on the Siple coast, the katabatic flow down the glaciers in the Eastern Ross Sea and the katabatic winds blowing from the Transantarctic Mountains, which are turned aside by Ross Island (Bromwich et al., 1998). In this work, the polynya opening and closure in 1999 is studied. A flux model (Biggs et al. 2000) is applied to a few case study in order to describe the polynya behaviour. Heat fluxes and sea ice production will be evaluated by using bulk formulae. The meteorological input for the calculations are provided by the European Center for Medium-range Weather Forecasting. Sea ice concentration data will be used in order to validate the model. Daily ice concentration data were retrieved by using the Sea Lion algorithm to obtain maps of the polynya area with a spatial resolution of 12.5x12.5km2 (Kern and Heygster, 2001; Kern, 2001). This is achieved using the polarization difference of 85GHz brightness temperatures acquired by the Special Sensor Microwave/Imager (SSM/I). This study focuses on the Ross Sea Polynya, but nevertheless the Terra Nova Bay polynya case will be investigated.

  5. Odd cloud in the Ross Sea, Antarctica

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On January 28, 2002, MODIS captured this image of an interesting cloud formation in the boundary waters between Antarctica's Ross Sea and the Southern Ocean. A dragon? A snake? A fish? No, but it is an interesting example of the atmospheric physics of convection. The 'eye' of this dragon-looking cloud is likely a small spot of convection, the process by which hot moist air rises up into the atmosphere, often producing big, fluffy clouds as moisture in the air condenses as rises into the colder parts of the atmosphere. A false color analysis that shows different kinds of clouds in different colors reveals that the eye is composed of ice crystals while the 'body' is a liquid water cloud. This suggests that the eye is higher up in the atmosphere than the body. The most likely explanation for the eye feature is that the warm, rising air mass had enough buoyancy to punch through the liquid water cloud. As a convective parcel of air rises into the atmosphere, it pushes the colder air that is higher up out of its way. That cold air spills down over the sides of the convective air mass, and in this case has cleared away part of the liquid cloud layer below in the process. This spilling over of cold air from higher up in the atmosphere is the reason why thunderstorms are often accompanied by a cool breeze. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  6. The Ross procedure at the crossroads: lessons from biology: is Dr Ross's dream concluded?

    PubMed

    Nappi, Francesco; Spadaccio, Cristiano; Al-Attar, Nawwar; Acar, Christophe

    2015-01-15

    The latest reports on the long-term outcome of Ross operation dropped a veil of uncertainty on the future of this life-saving procedure. The potential for pulmonary autograft dilation and failure in growing children led to resize the importance of this operation and favored the reappraisal of other techniques. Nevertheless, the idea of using the autologous pulmonary trunk to replace the diseased aortic valve remains an "evergreen" and techniques of reinforcement of the pulmonary autograft with synthetic materials have been developed. However, these strategies did not produce the expected benefits and the reasons underlying their failure need to be found in the fact that these materials do not respect tissue and cellular biology of a living and growing structure. A renovated attention should be paid to the biological processes occurring after our intervention and to the lessons that the nature wants to give us. Data on experimental approaches obeying to these warnings and respecting biological processes are increasingly available and we believe that this could be a key point to give an immediate future to the Ross procedure and to stimulate further research on the development of bio-artificial vascular substitutes. PMID:25464215

  7. Seismicity in the vicinity of Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Rowe, C. A.; Kienle, J.

    1986-12-01

    Earthquakes in the Ross Sea, Antarctica, are of two types: volcanic, and those which appear to be of tectonic origin. Volcanic events in the vicinity of Ross Island are associated exclusively with Mount Erebus, Ross Island; this volcano erupts regularly, generating several earthquakes per day whose characteristics are quite distinct from non-volcanic events. These nonvolcanic earthquakes are recognizable by their distinct P- and S-wave arrivals, and a lack of the high frequency, often monochromatic character typical of Erebus events. One hundred fifty-seven tectonic microearthquakes (M < 2.0) were recorded in 1983 and 1984 by the ten station network on Ross Island; these events were located using the least-squares routine, HYPOELLIPSE. Of these events, 106 have RMS residual traveltime errors of less than or equal to 0.6 seconds; they are clustered in the vicinity of Ross Island, but are not restricted to it. There is a linear trend of epicenters cutting across the island and continuing northward. Most activity seems to center beneath Mount Terra Nova, between Mount Erebus and Mount Terror. Mean depth for events is 8.2 km; however, depths are rather evenly distributed over a range of 0 to 25 km. Modelling based on Bouger gravity anomalies and seismic refraction studies indicates a depth to the Moho of about 40 km beneath the continent, shallowing to 27 km beneath the Ross Sea. This 27 km depth is approximately equal to the lower limit of the tectonic seismicity detected by the Erebus network; hence, events are of crustal origin. These data suggest, with the rift-type geochemistry of Erebus' magma, that the Ross Sea is a site of active crustal extension and rifting.

  8. B-15 iceberg family in the Ross Sea, Antarctica

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This true-color Moderate Resolution Imaging Spectroradiometer (MODIS) image from September 17, 2000, shows the B15 family of icebergs that calved off the Ross Ice Shelf in March of 2000, at the end of the Antarctic summer melt season. The enormous bergs were locked up in winter sea ice before they could drift very far that first season, but at the onset of the winter thaw, soon after this image was acquired, the bergs began to drift. The large, southernmost berg is B-15, and it eventually drifted over toward Ross Island, seen at the bottom left of the image. The amazing shadow being cast on the ground south of Ross Island is from Mt. Erebus.

  9. Science opportunities using the NASA scatterometer on N-ROSS

    NASA Technical Reports Server (NTRS)

    Freilich, M. H.

    1985-01-01

    The National Aeronautics and Space Administration scatterometer (NSCAT) is to be flown as part of the Navy Remote Ocean Sensing System (N-ROSS) scheduled for launch in 1989. The NSCAT will provide frequent accurate and high-resolution measurements of vector winds over the global oceans. NSCAT data will be applicable to a wide range of studies in oceanography, meteorology, and instrument science. The N-ROSS mission, is outlined, are described. The capabilities of the NSCAT flight instrument and an associated NASA research ground data-processing and distribution system, and representative oceanographic meteorological, and instrument science studies that may benefit from NSCAT data are surveyed.

  10. Four Asteroids and a Question Mark: Chasing Ross' Variables

    NASA Astrophysics Data System (ADS)

    Bedient, James

    2004-06-01

    F. E. Ross published a series of papers in 1925-1931 listing 379 new variable stars discovered during his search for high-proper-motion stars. In the years since then 271 have been studied and catalogued in the General Catalogue of Variable Stars. This paper identifies four of the remainder as asteroids, and discusses interesting observations of another.

  11. Generalization of Moll Ross relations for heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Mohammad, S. Noor

    2002-04-01

    Moll-Ross relations for the current flow through the base region of a bipolar transistor, and for the base transit time, have been generalized for heterojunction bipolar transistors with a nonuniform energy bandgap in the base region. The effect of both heavy doping and carrier degeneracy has been taken into account.

  12. John Ross--The Story of an American Indian.

    ERIC Educational Resources Information Center

    Harrell, Sara Gordon

    First elected Principal Chief of the Cherokee Nation in 1828, John Ross served his people with courage and honor through a difficult and tragic period in their history. Born in 1790, he grew up when the Cherokees' world was rapidly changing and treaties with federal and state governments ended in broken promises and the loss of Cherokee lands. He…

  13. Frank Elmore Ross and his Variable Star Discoveries

    NASA Astrophysics Data System (ADS)

    Osborn, Wayne

    2011-05-01

    Frank Elmore Ross (1874-1960) was a talented astronomer that excelled in such diverse fields as computational astronomy, optical instrument design and astrophotography. Today he is remembered in astronomy mainly for his lists of stars of high proper motion, many of which are among our closest neighbors. A by-product of his searches for high proper motion stars was the discovery of 379 new variable stars. The identities of a number of these "Ross variables" are still uncertain and the variability yet to be confirmed more than eighty years after publication, largely due to imprecise or erroneous coordinates. Ross's original observing cards and plates have been located and are being used to re-examine the stars. The cases of uncertain identity or variability are being resolved, and better magnitudes are being determined for these early-epoch observations. Many of the Ross variables are poorly studied and follow-up observations of a few of these stars have yielded some interesting results.

  14. Identification of oscillations in Ross Sea current data

    SciTech Connect

    Grumbine, R.W. )

    1987-01-01

    As part of the Pelagic Ross Ice Shelf Measurement project, 29 current meters were deployed in the Ross Sea near the ice-shelf edge during the 1983 and 1984 field seasons. The data from these meters give current speed and direction every hour for over a year in most locations. These data should reveal the characteristics of Ross Sea ocean circulation and indicate which processes are most important in ventilating the cavity below the Ross Ice Shelf. One way to analyze these data is to identify periodicity in the currents and thereby to obtain a characteristic fingerprint of ocean dynamics. If the periods in the currents are found to be the same as tidal or season, for example, then the currents are probably caused by tidal or seasonal forcing. To identify such periodicity, a method is needed to discriminate between natural periodicities and apparent periodicities caused by measurement error and random fluctuations. The author used the deviation of current amplitude from the estimated trend to judge the significance of the period tested. He also required that a given periodicity be considered significant on several (at least three) of the current meters before concluding that it was probably physical. Although this method for identifying periods was developed for velocity analysis, it will work for other times series, such as temperature. Results are given.

  15. Scavenging amphipods from under the Ross Ice Shelf, Antarctica

    NASA Astrophysics Data System (ADS)

    Stockton, William L.

    1982-07-01

    Amphipods in the genus Orchomene were collected from under the Ross Ice Shelf, Antarctica, 400 km from the shelf edge at a depth of 600 m. A study of 992 individuals of the 3500 captured revealed that the population is dominated by the larger size classes. Two-thirds of the population is composed of males. Ovigerous females will approach and consume bait and females are multiply brooded. The source of nutrition for this population is not definitely known. Identifiable gut contents were bacteria mixed with sediment, pieces of crustacean carapaces, and tissue from apparently cannibalized conspecifics. It is an open question as to whether the population sampled is persistent over time and whether amphipods are common under all of the Ross Ice Shelf.

  16. Validation of Robotic Surgery Simulator (RoSS).

    PubMed

    Kesavadas, Thenkurussi; Stegemann, Andrew; Sathyaseelan, Gughan; Chowriappa, Ashirwad; Srimathveeravalli, Govindarajan; Seixas-Mikelus, Stéfanie; Chandrasekhar, Rameella; Wilding, Gregory; Guru, Khurshid

    2011-01-01

    Recent growth of daVinci Robotic Surgical System as a minimally invasive surgery tool has led to a call for better training of future surgeons. In this paper, a new virtual reality simulator, called RoSS is presented. Initial results from two studies - face and content validity, are very encouraging. 90% of the cohort of expert robotic surgeons felt that the simulator was excellent or somewhat close to the touch and feel of the daVinci console. Content validity of the simulator received 90% approval in some cases. These studies demonstrate that RoSS has the potential of becoming an important training tool for the daVinci surgical robot. PMID:21335803

  17. Rosse, 3rd Earl of [William Parsons, Lord Rosse, Lord Oxmantown] (1800-67) and Rosse, 4th Earl of [Laurence Parsons, Lord Rosse, Lord Oxmantown] (1840-1908)

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Irish astronomer and landowner, the 3rd Lord Rosse was educated at Trinity College, Dublin and Oxford as a mathematician. He became interested in astronomy and made at the family castle in Birr a 36 in reflector with the same design as William Herschel's (see HERSCEL FAMILY). Mapped the Moon, and observed nebulae with the intent to resolve them into stars. He developed the technology at Birr Cast...

  18. Trophic interactions within the Ross Sea continental shelf ecosystem

    PubMed Central

    Smith, Walker O; Ainley, David G; Cattaneo-Vietti, Riccardo

    2006-01-01

    The continental shelf of the Ross Sea is one of the Antarctic's most intensively studied regions. We review the available data on the region's physical characteristics (currents and ice concentrations) and their spatial variations, as well as components of the neritic food web, including lower and middle levels (phytoplankton, zooplankton, krill, fishes), the upper trophic levels (seals, penguins, pelagic birds, whales) and benthic fauna. A hypothetical food web is presented. Biotic interactions, such as the role of Euphausia crystallorophias and Pleuragramma antarcticum as grazers of lower levels and food for higher trophic levels, are suggested as being critical. The neritic food web contrasts dramatically with others in the Antarctic that appear to be structured around the keystone species Euphausia superba. Similarly, we suggest that benthic–pelagic coupling is stronger in the Ross Sea than in most other Antarctic regions. We also highlight many of the unknowns within the food web, and discuss the impacts of a changing Ross Sea habitat on the ecosystem. PMID:17405209

  19. Qualification test of the Ross Double Planetary Mixer

    NASA Astrophysics Data System (ADS)

    Lueders, Kurt F.

    1993-07-01

    This test report describes the qualification test of the Ross Double Planetary Mixer used to mix room temperature vulcanized (RTV) silicone (Dow Corning 90-006-2) for the redesigned solid rocket motor (RSRM) nozzle joints. Testing was completed 18 June 1993 in the M-113A Nozzle Fabrication Facility at Thiokol Corporation, Space Operations, Brigham City, Utah. The Ross mixer provides better mixing and better control on temperature and humidity, resulting in better quality RTV and a longer usable pot life. The test began on 3 May 1993 and was stopped due to operator error during the tensile strength and elongation testing. Specimens were ruined without gathering any useful data. A 'no test' was declared, the problem was remedied, and the test was re-run with MSFC approval. The test was run and all pass/fail criteria were met, most with a considerable margin. The Ross Double Planetary Mixer met all certification objectives and is recommended for immediate use for mixing RTV silicone for RSRM nozzle joints.

  20. Formative Processes Governing Ross Sea Polynya Areal Variability

    NASA Astrophysics Data System (ADS)

    Ward, J. M.

    2014-12-01

    Of the 17 million km^2 of sea ice in the Southern Ocean, ~10% is generated through coastal polynyal systems. The largest and greatest contributor to sea ice formation in the Antarctic is the Ross Sea Polynya which exists in a region where sea ice trends are positive and significant. Understanding polynya areal dynamics and the contributing physical factors will give further insight into the future of Ross Sea ice production. Previous studies have established coastal winds and surface temperatures as key contributors to the development and maintenance of coastal polynyas. However, much that is understood is based on physically sound inference. While the influence of these variables have been studied separately, their concerted roles have not been quantified, neither has any indication of their variation with time been established. Automatic weather station data produced by the Antarctic Automatic Weather Station Program was acquired from the National Oceanic and Atmospheric Administration, and polynya area data was produced through the application of the Polynya Signature Simulation Method onto Special Sensor Microwave Imager input acquired from the National Snow and Ice Data Center. Wind speed, wind direction, sea surface temperature, near surface air temperature, oceanic temperature, and tidal fluctuations are examined as physically significant contributors to polynya areal variability and are considered in a multivariate regression model at a 95% confidence level. This study quantifies the degree to which each variable contributes to Ross Sea Polynya areal dynamics, and determines how their influences vary seasonally and in the long term.

  1. The Hillary Canyon and the Iselin Bank (Eastern Ross Sea, Antarctica): Alongslope and Downslope Route For Ross Sea Bottom Water

    NASA Astrophysics Data System (ADS)

    De Santis, L.; Bergamasco, A.; Colizza, E.; Geletti, R.; Accaino, F.; Wardell, N.; Olivo, E.; Petronio, L.; Henrys, S. A.; Black, J.; Mckay, R. M.; Bohm, G.

    2015-12-01

    The modern seabed of the Antarctic continental slope generally does not show a rugged geomorphology. Channel systems incise the lower continental rise, but in most cases they are inherited features formed as channel-levee turbiditic systems during past, more temperate times. The Hillary Canyon cuts the eastern Ross Sea continental slope and rise, to the Southeast of the Iselin Bank, and is directly connected to the Glomar Challenger Trough on the continental shelf. Cold dense salty water forms today in the Ross Sea polynya, spreads below the Ross Ice Shelf, becomes supercooled, fills up the landward deepening Glomar Challenger Trough and then spills over the sill of the shelf edge and flows downslope, often along the Hillary Canyon, in a geostrophic way, deviated westwards by the Coriolis Force, but sometimes also with a cascading a-geostrophic behaviour. This supercold water signal was found on the continental slope down to 1200 m depth. The shape of this tongue of modified ISW, whose thickness reaches up to 100 m, is very narrow, suggesting that the overflow occurs in very localized areas along the slope. Here we combine seismic stratigraphy analysis of multichannel seismic reflection profiles, box and gravity cores in the Hillary Canyon and along the eastern flank of the Iselin Bank, with seabed bathymetry and numerical modelling of thevertical and spatial distribution of the water masses, in order to identify modern and past pathways of the Ross Sea Bottom Water current. The results of this work show that the Hillary Canyon and the sediment mounds that formed along its flanks have been active since early Miocene times. Sediment drift-moat features and sediment waves are indicative of strong Northwest bottom currents reworking the seabed sediments at different water depths along the slope, possibly since the late Miocene. These sediment drifts are some of the targets of the IODP proposal 751-full.

  2. Amphibian Seismological Studies in the Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Schmidt-Aursch, Mechita; Kuk Hong, Jong; Lee, Won Sang; Geissler, Wolfram; Yun, Sukyoung; Gohl, Karsten; Park, Yongcheol; Yoo, Hyun Jae

    2016-04-01

    The Antarctic Ross Sea is one of the key regions for polar research activities. Research stations from several countries located at the coast are the base for inland expeditions. Even in the austral summer, the Ross Sea is party covered with drifting ice fields; this requires an icebreaker for all marine explorations. Therefore, large geophysical surveys in the Ross Sea are difficult. But the area is of special interest for seismologists: The Terror Rift in the western Ross Sea is a prominent neotectonic structure of the West Antarctic Rift System (WARS). It is located near the coast in the Victoria Land Basin and extends parallel to the Transantarctic Mountains. The rifting processes and the accompanying active onshore volcanism lead to increased seismicity in the region. The annual waxing and waning of the sea-ice and the dynamics of the large Ross Ice Shelf and nearby glaciers generate additional seismic signals. Investigation on seismological activities associated with the WARS and the cryogenic signals simultaneously would give us an unprecedented opportunity to have a better understanding of the Evolution of the WARS (EWARS) and the rapid change in the cryospheric environment nearby. The Korea Polar Research Institute (KOPRI) and the Alfred-Wegener-Institut (AWI) have conducted a pilot study off the Korean Jang Bogo research station in the Terra Nova Bay by developing a collaborative research program (EWARS) since 2011 to explore seismicity and seismic noise in this region. Four broadband ocean-bottom seismometers (OBS) from the German DEPAS pool were deployed in January 2012 with the Korean research icebreaker RV Araon. Three instruments could successfully be recovered after 13 months, the fourth OBS was not accessible due to local sea-ice coverage. We have successfully completed a second recovery operation in January 2014. All stations recorded data of good quality, one station stopped after 8 months due to a recorder error. The OBS recovered in 2014

  3. A systematic technical approach to the Ross operation.

    PubMed

    Joyce, F; Tingleff, J; Pettersson, G

    1996-07-01

    The Ross operation is a technically demanding procedure. The pressure on the surgeon to produce consistently good results from the very first operation is great, since he is not afforded the luxury of a very soft "learning curve", as is the case with many technically difficult operations, due to the availability of acceptable and safe alternatives for most Ross candidates. We have felt this pressure from the outset and this has motivated a commitment to the development of a systematic surgical technique in an attempt to achieve consistently excellent results. Maintenance of normal autograft spatial geometry after translocation to the aortic position is necessary to ensure proper leaflet coaptation and to avoid autograft insufficiency, and this is the underlying principle upon which this technique is based. Most Ross operations are now performed as total aortic root replacements with a free-standing autograft, However, the autograft is soft and compliant, and will adapt to the dimensions of the more solid tissue into which it is inserted, the aortic annulus proximally and ascending aorta distally, and root replacement will not guarantee that normal autograft geometry will be maintained unless there is a correct size match between the autograft and the aortic annulus and sino-tubular junction, and the autograft is not distorted in other ways. A systematic technical approach to the Ross operation so that size mismatch is avoided and autograft geometry is maintained has been developed and is described in step-by-step detail. In the first third of this series of 85 patients, two patients had moderate (2+) and three patients had mild (1+) immediate postoperative autograft insufficiency. As our understanding of the important sizing and orientation issues has increased and the systematic technique has evolved, the incidence of early autograft insufficiency has essentially been eliminated. In the latter 2/3 of the series, all patients had less than mild autograft

  4. Ross Ice Shelf Seismic Survey and Future Drilling Recommendation

    NASA Astrophysics Data System (ADS)

    van Haastrecht, Laurine; Ohneiser, Christian; Gorman, Andrew; Hulbe, Christina

    2016-04-01

    The Ross Ice Shelf (RIS) is one of three gateways through which change in the ocean can be propagated into the interior of West Antarctica. Both the geologic record and ice sheet models indicate that it has experienced widespread retreat under past warm climates. But inland of the continental shelf, there are limited data available to validate the models. Understanding what controls the rate at which the ice shelf will respond to future climate change is central to making useful climate projections. Determining the retreat rate at the end of the last glacial maximum is one part of this challenge. In November 2015, four lines of multi-channel seismic data, totalling over 45 km, were collected on the Ross Ice Shelf, approximately 300 km south of Ross Island using a thumper seismic source and a 96 channel snow streamer. The seismic survey was undertaken under the New Zealand Antarctic Research Institute (NZARI) funded Aotearoa New Zealand Ross Ice Shelf Programme to resolve bathymetric details and to image sea floor sediments under a proposed drilling site on the ice shelf, at about 80.7 S and 174 E. The thumper, a purpose-built, trailer mounted, weight-drop seismic source was towed behind a Hägglund tracked vehicle to image the bathymetry and sediments underneath the RIS. Seismic data collection on an ice shelf has unique challenges, in particular strong attenuation of the seismic energy by snow and firn, and complex multiple ray paths. The thumper, which consists of a heavy weight (250kg) that is dropped on a large, ski mounted steel plate, produced a consistent, repeatable higher energy signal when compared to sledge hammer source and allowed for a greater geographic coverage and lower environmental impact than an explosive source survey. Our survey revealed that the seafloor is smooth and that there may be up to 100 m of layered sediments beneath the seafloor and possibly deeper, more complex structures. A multiple generated by internally reflected seismic energy

  5. Unique manifestations of mixed-phase cloud microphysics over Ross Island and the Ross Ice Shelf, Antarctica

    NASA Astrophysics Data System (ADS)

    Scott, Ryan C.; Lubin, Dan

    2016-03-01

    Spaceborne radar and lidar observations from the CloudSat and CALIPSO satellites are used to compare seasonal variations in the microphysical and radiative properties of clouds over Ross Island, Antarctica, with two contrasting Arctic atmospheric observatories located in Barrow, Alaska, and Summit, Greenland. At Ross Island, downstream from recurrent intrusions of marine air over the West Antarctic Ice Sheet and eastern Ross Ice Shelf, clouds exhibit a tendency toward the greatest geometrical thickness and coldest temperatures in summer, the largest average ice water content, IWC, at low altitude during summer and autumn, the most abundant IWC at cold mixed-phase temperatures (-40°C

  6. Early Miocene Tectonic Activity in the western Ross Sea (Antarctica)

    NASA Astrophysics Data System (ADS)

    Sauli, C.; Sorlien, C. C.; Busetti, M.; Geletti, R.; De Santis, L.

    2012-12-01

    In the framework of the Rossmap Italian PNRA work objectives to compile extended and revised digital maps of the main unconformities in Ross Sea, Antarctica, much additional seismic reflection data, that were not available to previous ANTOSTRAT compilation, were incorporated into a new ROSSMAP interpretation. The correlation across almost all of Ross Sea, from DSDP Site 270 and Site 272 in Eastern Basin to northern Victoria Land Basin, of additional early Miocene and late Oligocene horizons that were not part of ANTOSTRAT allows interpretations to be made of fault activity and glacial erosion or deposition at a finer time resolution. New conclusions include that extensional or transtensional fault activity within the zone between Victoria Land Basin and Northern Basin, initiated by 23 Ma or earlier, and continued after 18 Ma. Steep parallel-striking faults in southern Victoria Land Basin display both reverse and normal separation of 17.5 Ma (from Cape Roberts Program-core 1) and post-16 Ma horizons, suggesting an important strike-slip component. This result may be compared with published papers that proposed post-17 Ma extension in southern Victoria Land Basin, 16-17 Ma extension in the AdareTrough, north of the Ross Sea continental shelf, but no Miocene extension affecting the Northern Basin (Granot et al., 2010). Thus, our evidence for extension through the early Miocene is significant to post-spreading tectonic models. Reference Granot R., Cande S. C., Stock J. M., Davey F. J. and Clayton R. W. (2010) Postspreading rifting in the Adare Basin, Antarctica: Regional tectonic consequences. Geochem. Geophys. Geosyst., 8, Q08005, doi:10.1029/2010GC003105.

  7. Cryptoendolithic lichen and cyanobacterial communities of the Ross Desert, Antarctica

    NASA Technical Reports Server (NTRS)

    Friedmann, E. I.; Hua, M.; Ocampo-Friedmann, R.

    1988-01-01

    Cryptoendolithic microbial communities in the Ross Desert (McMurdo Dry Valleys) are characterized on the basis of photosynthetic microorganisms and fungi. Two eukaryotic communities (the lichen-dominated and Hemichloris communities) and three cyanobacterial communities (the red Gloeocapsa, Hormathonema-Gloeocapsa, and Chroococcidiopsis communities) are described. Eleven coccoid, one pleurocapsoid, and five filamentous cyanobacteria occurring in these communities are characterized and illustrated. The moisture grade of the rock substrate seems to affect pH, formation of primary iron stain, and the distribution of microbial communities.

  8. STS-88 Mission Specialists Currie and Ross inside Endeavour

    NASA Technical Reports Server (NTRS)

    1998-01-01

    STS-88 Mission Specialists Nancy J. Currie, Ph.D., (back) and Jerry L. Ross (front) check over equipment inside orbiter Endeavour during Terminal Countdown Demonstration Activities (TCDT). The TCDT includes mission familiarization activities, emergency egress training, and the simulated main engine cut-off exercise. Mission STS-88 is targeted for launch on Dec. 3, 1998. It is the first U.S. flight for the assembly of the International Space Station and will carry the Unity connecting module. Unity will be mated with the already orbiting Russian-built Zarya control module. The 12-day mission includes three planned spacewalks to connect power, data and utility lines and install exterior equipment.

  9. Frank Elmore Ross and His Variable Star Discoveries

    NASA Astrophysics Data System (ADS)

    Osborn, W.

    2012-06-01

    Frank Ross (1874-1960) was a talented astronomer that excelled in such diverse fields as computational astronomy, optical instrument design, and astrophotography. His career and astronomical contributions are briefly summarized. One contribution was finding 379 probable new variable stars. Most of these variables are poorly studied, and for a number the identifications are still uncertain and the variability not yet confirmed more than eighty years after publication. Ross’s original observing cards and plates are being used to re-examine the stars and resolve the problem cases. Follow-up work on a few stars has yielded interesting results. This work is illustrated with one example.

  10. STS-61B Astronaut Ross During ACCESS Extravehicular Activity

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The crew assigned to the STS-61B mission included Bryan D. O'Conner, pilot; Brewster H. Shaw, commander; Charles D. Walker, payload specialist; mission specialists Jerry L. Ross, Mary L. Cleave, and Sherwood C. Spring; and Rodolpho Neri Vela, payload specialist. Launched aboard the Space Shuttle Atlantis November 28, 1985 at 7:29:00 pm (EST), the STS-61B mission's primary payload included three communications satellites: MORELOS-B (Mexico); AUSSAT-2 (Australia); and SATCOM KU-2 (RCA Americom). Two experiments were conducted to test assembling erectable structures in space: EASE (Experimental Assembly of Structures in Extravehicular Activity), and ACCESS (Assembly Concept for Construction of Erectable Space Structure). In a joint venture between NASA/Langley Research Center in Hampton, Virginia and the Marshall Space Flight Center (MSFC), EASE and ACCESS were developed and demonstrated at MSFC's Neutral Buoyancy Simulator (NBS). The primary objective of this experiment was to test the structural assembly concepts for suitability as the framework for larger space structures and to identify ways to improve the productivity of space construction. In this STS-61B onboard photo, astronaut Ross was working on the ACCESS experiment during an Extravehicular Activity (EVA).

  11. STS-61B Astronaut Ross During ACCESS Extravehicular Activity

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The crew assigned to the STS-61B mission included Bryan D. O'Conner, pilot; Brewster H. Shaw, commander; Charles D. Walker, payload specialist; mission specialists Jerry L. Ross, Mary L. Cleave, and Sherwood C. Spring; and Rodolpho Neri Vela, payload specialist. Launched aboard the Space Shuttle Atlantis November 28, 1985 at 7:29:00 pm (EST), the STS-61B mission's primary payload included three communications satellites: MORELOS-B (Mexico); AUSSAT-2 (Australia); and SATCOM KU-2 (RCA Americom). Two experiments were conducted to test assembling erectable structures in space: EASE (Experimental Assembly of Structures in Extravehicular Activity), and ACCESS (Assembly Concept for Construction of Erectable Space Structure). In a joint venture between NASA/Langley Research Center in Hampton, VA and the Marshall Space Flight Center (MSFC), ACCESS and EASE were developed and demonstrated at MSFC's Neutral Buoyancy Simulator (NBS). In this STS-61B onboard photo, astronaut Ross was working on the ACCESS experiment during an Extravehicular Activity (EVA). The primary objective of this experiment was to test the ACCESS structural assembly concept for suitability as the framework for larger space structures and to identify ways to improve the productivity of space construction.

  12. The Oceanography and Ecology of the Ross Sea

    NASA Astrophysics Data System (ADS)

    Smith, Walker O.; Ainley, David G.; Arrigo, Kevin R.; Dinniman, Michael S.

    2014-01-01

    The continental shelf of the Ross Sea exhibits substantial variations in physical forcing, ice cover, and biological processes on a variety of time and space scales. Its circulation is characterized by advective inputs from the east and exchanges with off-shelf regions via the troughs along the northern portions. Phytoplankton biomass is greater there than anywhere else in the Antarctic, although nitrate is rarely reduced to levels below 10 μmol L-1. Overall growth is regulated by irradiance (via ice at the surface and by the depths of the mixed layers) and iron concentrations. Apex predators reach exceptional abundances, and the world's largest colonies of Adélie and emperor penguins are found there. Krill are represented by two species (Euphausia superba near the shelf break and Euphausia crystallorophias throughout the continental shelf region). Equally important and poorly known is the Antarctic silverfish (Pleuragramma antarcticum), which is also consumed by most upper-trophic-level predators. Future changes in the Ross Sea environment will have profound and unpredictable effects on the food web.

  13. Seasonal and diurnal calling patterns of Ross and leopards

    NASA Astrophysics Data System (ADS)

    Rogers, Tracey L.; Rowney, Gayle A.; Ciaglia, Michaela B.; Cato, Douglas H.

    2005-09-01

    The temporal calling patterns of two Antarctic pack ice seals, the leopard and Ross seal, were examined. This included seasonal onset and decline of calling (coinciding with their breeding season) as well as diurnal changes. Understanding of calling behavior has important implications for acoustic surveying, since this allows the number of calls to be related to an index of the number of animals present and to estimate abundance. The monthly changes in diurnal calling and haul-out patterns (measured via satellite telemetry) were compared. Underwater acoustic recordings were made between 14 October 2003 and 10 January 2004 off Mawson, Eastern Antarctica (660 44.243S and 690 48.748E). Recordings were made using an Acoustics Recording Package (ARP by Dr. John Hildebrand, Scripps Institute of Oceanography, La Jolla, CA) which is designed to sit on the seafloor and passively record acoustic signals. The package was deployed at a depth of 1320.7 m. The sampling rate was 500 Hz and the effective bandwidth from 10 to 250 Hz, covering the bandwidth of only the low-frequency calls of the Ross and leopard seal.

  14. 75 FR 32802 - Certificate of Alternative Compliance for the Offshore Supply Vessel ROSS CANDIES

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-09

    ... SECURITY Coast Guard Certificate of Alternative Compliance for the Offshore Supply Vessel ROSS CANDIES... Alternative Compliance was issued for the offshore supply vessel ROSS CANDIES as required by 33 U.S.C. 1605(c... CANDIES, O.N. 1222260. Full compliance with 72 COLREGS ] would hinder the vessel's ability to...

  15. The Re-construction of the 6-foot Rosse Telescope of Ireland

    NASA Astrophysics Data System (ADS)

    Tubridy, Michael

    An article describing the reconstruction and restoration efforts by Michael Tubridy, the engineer of the project, of the Lord Rosse Leviathan of Parsonstown, a 6-foot telescope, and the first to reveal spiral structure in galaxies, and a brief biography on the third Earl of Rosse, William Parsons.

  16. Does temperature structure phytoplankton community composition in the Ross Sea, Antarctica?

    EPA Science Inventory

    The Ross Sea polynya experiences one of the largest phytoplankton blooms in the Southern Ocean. Energy flow potential within the Ross Sea food web is primarily set by diatoms and prymnesiophytes, the latter dominated by Phaeocystis antarctica. We investigated physical, chemical,...

  17. Decadal trends in air-sea CO2 exchange in the Ross Sea (Antarctica)

    NASA Astrophysics Data System (ADS)

    Tagliabue, Alessandro; Arrigo, Kevin R.

    2016-05-01

    Highly productive Antarctic shelf systems, like the Ross Sea, play important roles in regional carbon budgets, but the drivers of local variations are poorly quantified. We assess the variability in the Ross Sea carbon cycle using a regional physical-biogeochemical model. Regionally, total partial pressure of CO2 (pCO2) increases are largely controlled by the biological pump and broadly similar to those in the offshore Southern Ocean. However, this masks substantial local variability within the Ross Sea, where interannual fluctuations in total pCO2 are driven by the biological pump and alkalinity, whereas those for anthropogenic pCO2 are related to physical processes. Overall, the high degree of spatial variability in the Ross Sea carbon cycle causes extremes in aragonite saturation that can be as large as long-term trends. Therefore, Antarctic shelf polynya systems like the Ross Sea will be strongly affected by local processes in addition to larger-scale phenomena.

  18. Past ice-sheet behaviour: retreat scenarios and changing controls in the Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Halberstadt, Anna Ruth W.; Simkins, Lauren M.; Greenwood, Sarah L.; Anderson, John B.

    2016-05-01

    Studying the history of ice-sheet behaviour in the Ross Sea, Antarctica's largest drainage basin can improve our understanding of patterns and controls on marine-based ice-sheet dynamics and provide constraints for numerical ice-sheet models. Newly collected high-resolution multibeam bathymetry data, combined with two decades of legacy multibeam and seismic data, are used to map glacial landforms and reconstruct palaeo ice-sheet drainage. During the Last Glacial Maximum, grounded ice reached the continental shelf edge in the eastern but not western Ross Sea. Recessional geomorphic features in the western Ross Sea indicate virtually continuous back-stepping of the ice-sheet grounding line. In the eastern Ross Sea, well-preserved linear features and a lack of small-scale recessional landforms signify rapid lift-off of grounded ice from the bed. Physiography exerted a first-order control on regional ice behaviour, while sea floor geology played an important subsidiary role. Previously published deglacial scenarios for Ross Sea are based on low-spatial-resolution marine data or terrestrial observations; however, this study uses high-resolution basin-wide geomorphology to constrain grounding-line retreat on the continental shelf. Our analysis of retreat patterns suggests that (1) retreat from the western Ross Sea was complex due to strong physiographic controls on ice-sheet drainage; (2) retreat was asynchronous across the Ross Sea and between troughs; (3) the eastern Ross Sea largely deglaciated prior to the western Ross Sea following the formation of a large grounding-line embayment over Whales Deep; and (4) our glacial geomorphic reconstruction converges with recent numerical models that call for significant and complex East Antarctic ice sheet and West Antarctic ice sheet contributions to the ice flow in the Ross Sea.

  19. Low-frequency microwave radiometer for N-ROSS

    NASA Technical Reports Server (NTRS)

    Hollinger, J. P.; Lo, R. C.

    1985-01-01

    The all weather, global determination of sea surface temperature (SST) has been identified as a requirement needed to support naval operations. The target SST accuracy is + or - 1.0 K with a surface resolution of 10 km. Investigations of the phenomenology and technology of remote passive microwave sensing of the ocean environment over the past decade have demonstrated that this objective is presently attainable. Preliminary specification and trade off studies were conducted to define the frequency, polarization, scan geometry, antenna size, and other esstential parameters of the low frequency microwave radiometer (LFMR). It will be a dual polarized, dual frequency system at 5.2 and 10.4 GHz using a 4.9 meter deployable mesh surface antenna. It is to be flown on the Navy-Remote Ocean Sensing System (N-ROSS) satellite scheduled to be launched in late 1988.

  20. A PERIODIC ROSS-MACDONALD MODEL IN A PATCHY ENVIRONMENT

    PubMed Central

    Gao, Daozhou; Lou, Yijun; Ruan, Shigui

    2014-01-01

    Based on the classical Ross-Macdonald model, in this paper we propose a periodic malaria model to incorporate the effects of temporal and spatial heterogeneity on disease transmission. The temporal heterogeneity is described by assuming that some model coefficients are time-periodic, while the spatial heterogeneity is modeled by using a multi-patch structure and assuming that individuals travel among patches. We calculate the basic reproduction number R0 and show that either the disease-free periodic solution is globally asymptotically stable if R0≤1 or the positive periodic solution is globally asymptotically stable if R0>1. Numerical simulations are conducted to confirm the analytical results and explore the effect of travel control on the disease prevalence. PMID:25473381

  1. Albert Ross Tilley: The legacy of a Canadian plastic surgeon.

    PubMed

    Mowbrey, Kevin

    2013-01-01

    The present article chronicles the career of Dr Albert Ross Tilley, one of the most important Canadian plastic surgeons of the 20th century. Tilley is most well known for his innovations of burn management during World War II and his treatment of a group of burn patients known affectionately as the 'Guinea Pig Club'. In addition to the superb surgical skills he applied to the physical wounds of his patients, Tilley was also a pioneer of caring for the emotional and psychological afflictions suffered by many airmen of World War II. As one of the founding fathers of the Canadian Society of Plastic Surgeons, Tilley's work was instrumental in establishing the specialty and ensured its prosperity for years to come. Serving in the capacity of leader, educator and innovator, Tilley remains one of Canada's most decorated physicians, and his body of work encompasses contributions to the medical field that remain significant and beneficial to patient care to this day. PMID:24431953

  2. Ross E. Baker, DC: A Canadian chiropractic survivor

    PubMed Central

    Brown, Douglas M.

    2014-01-01

    This paper is an historical biography of a fortunate man. It begins with a glimpse of Ross E. Baker’s origins in south-western Ontario, watches him going to school and working in Hamilton before joining the Canadian Army and shipping off to Europe to fight in the Second World War. At War’s end, the article picks up Dr. Baker as he comes home, starts a family, becomes a chiropractor and sustains a viable practice. Now in the twilight of life, the good doctor is last seen content with his retirement, spending days at his cottage property, reviewing his memoirs and reflecting on the tumult, terror and eventual triumph of the D-Day landing at Normandy. PMID:24587499

  3. [A reappraisal of the works of Elisabeth Kubler-Ross].

    PubMed

    Afonso, Selene Beviláqua Chaves; Minayo, Maria Cecília de Souza

    2013-09-01

    This article presents a reappraisal of part of the works of Elizabeth Kubler-Ross, one of the most quoted authors addressing the end of life process, mourning and dying. Her work has contributed to a clearer understanding of these issues by health professionals, families, religious and lay people who handle and/or experience mourning. She has also been the subject of controversy related to ethical issues and the scientific rigor of her work. The books analyzed in this article are: On death and dying (1969); Questions and answers on death and dying (1971); Living with death and dying (1981); On children and death(1983); On life after death (1991) and Life lessons (2000). PMID:23989580

  4. Gaussian estimation for discretely observed Cox-Ingersoll-Ross model

    NASA Astrophysics Data System (ADS)

    Wei, Chao; Shu, Huisheng; Liu, Yurong

    2016-07-01

    This paper is concerned with the parameter estimation problem for Cox-Ingersoll-Ross model based on discrete observation. First, a new discretized process is built based on the Euler-Maruyama scheme. Then, the parameter estimators are obtained by employing the maximum likelihood method and the explicit expressions of the error of estimation are given. Subsequently, the consistency property of all parameter estimators are proved by applying the law of large numbers for martingales, Holder's inequality, B-D-G inequality and Cauchy-Schwarz inequality. Finally, a numerical simulation example for estimators and the absolute error between estimators and true values is presented to demonstrate the effectiveness of the estimation approach used in this paper.

  5. STS-110 Astronaut Jerry Ross Performs Extravehicular Activity (EVA)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Launched aboard the Space Shuttle Orbiter Atlantis on April 8, 2002, the STS-110 mission prepared the International Space Station (ISS) for future space walks by installing and outfitting the 43-foot-long Starboard side S0 (S-zero) truss and preparing the first railroad in space, the Mobile Transporter. The 27,000 pound S0 truss was the first of 9 segments that will make up the Station's external framework that will eventually stretch 356 feet (109 meters), or approximately the length of a football field. This central truss segment also includes a flatcar called the Mobile Transporter and rails that will become the first 'space railroad,' which will allow the Station's robotic arm to travel up and down the finished truss for future assembly and maintenance. The completed truss structure will hold solar arrays and radiators to provide power and cooling for additional international research laboratories from Japan and Europe that will be attached to the Station. STS-110 Extravehicular Activity (EVA) marked the first use of the Station's robotic arm to maneuver space walkers around the Station and was the first time all of a shuttle crew's space walks were based out of the Station's Quest Airlock. In this photograph, Astronaut Jerry L. Ross, mission specialist, anchored on the end of the Canadarm2, moves near the newly installed S0 truss. Astronaut Lee M. E. Morin, mission specialist, (out of frame), worked in tandem with Ross during this fourth and final scheduled session of EVA for the STS-110 mission. The final major task of the space walk was the installation of a beam, the Airlock Spur, between the Quest Airlock and the S0. The spur will be used by space walkers in the future as a path from the airlock to the truss.

  6. Winter Habitat Preference of Weddell Seals in the Ross Sea

    NASA Astrophysics Data System (ADS)

    Goetz, K. T.; Costa, D. P.; Robinson, P.; Burns, J. M.; Pearson, L.

    2010-12-01

    Weddell seals are important top predators in the Southern Ocean, yet very little data exist on their overwinter diving and foraging behavior when darkness and heavy ice cover prevail. To gain insight on both Weddell seal ecology and the oceanography of the Ross Sea during the winter, we outfitted 22 animals around Ross Island and up the Victorialand coast with Conductivity Temperature Depth - Satellite Relayed Data Logger (CTD-SRDL) tags. To date, over 75,000 dives and 4,000 CTD casts have been recorded. On average, Weddell seals dived to 210 m with a max dive depth of 969 m for nearly an hour in duration. While many seals spent a substantial amount of time in the area where they were tagged, several animals traveled over 1000 km from the tag deployment location: twice as far as shown in previous studies. Areas near Roosevelt and Coulman Islands appear to be important for Weddell seals as indicated by the increased diving per square kilometer. In fact, diving density, transit rate, and time spent in a given area reveal identical ‘hotspots’, possible foraging locations. While there appears to be some individual variation, Weddell seals prefer low slope (flat benthos) and water depths between 350 and 550 meters. Using the seal-generated temperature and conductivity casts, we also report the oceanographic conditions in these areas to gain a better understanding of Weddell seal habitat preferences and behavior in relation to oceanographic features. Obtaining information on how Weddell seals respond to their environment is necessary to predict how seal populations in highly dynamic systems are likely to respond to shifting environmental conditions associated with global climate change. Forage index for Weddell seals after correcting for tagging location

  7. Structural framework and hydrocarbon potential of Ross Sea, Antarctica

    SciTech Connect

    Cooper, A.K.; Davey, F.J.

    1987-05-01

    The 400 to 1100-m deep continental shelf of the Ross Sea is underlain by three major sedimentary basins (Eastern basin, Central trough, and Victoria Land basin), which contain 5 to 6 km of sedimentary rock of Late Cretaceous(.) and younger age. An addition 6 to 7 km of older sedimentary and volcanic rocks lie within the Victoria Land basin. Eroded basement ridges of early Paleozoic(.) and older rocks similar to those of onshore Victoria Land separate the basins. The three basins formed initially in late Mesozoic time during an early period of rifting between East and West Antarctica. The Eastern basin is a 300-km wide, asymmetric basement trough that structurally opens into the Southern Ocean. A seaward-prograding sequence of late Oligocene and younger glacial deposits covers a deeper, layered sequence of Paleogene(.) and older age. The Central trough, a 100-km wide depression, is bounded by basement block faults and is filled with a nearly flat-lying sedimentary section. A prominent positive gravity anomaly, possibly caused by rift-related basement rocks, lies along the axis of the basin. The Victoria Land basin, unlike the other two basins, additionally contains a Paleogene(.) to Holocene rift zone, the Terror Rift. Rocks in the rift, near the axis of the 150-km wide basement half-graben, show extensive shallow faulting and magmatic intrusion of the sedimentary section. The active Terror rift and older basin structures extend at least 300 km along the base of the Transantarctic Mountains. Petroleum hydrocarbons have not been reported in the Ross Sea region, with possible exception of ethane gas found in Deep Sea Drilling Project cores from the Eastern basin. Model studies indicate that hydrocarbons could be generated at depths of 3.5 to 6 km within the sedimentary section. The best structures for hydrocarbon entrapment occur in the Victoria Land basin and associated Terror Rift.

  8. Two-dimensional Tomographic Inversion Model of Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Maraj, S.; Aster, R. C.; Knox, H. A.; Zandomeneghi, D.; Snelson, C. M.; Kyle, P. R.

    2010-12-01

    A controlled-source seismic refraction experiment (Tomo-Erebus; TE) was undertaken during the 2008-09 Austral summer field season to examine the magmatic system beneath the active Erebus volcano (TE-3D) and the crustal structure beneath Ross Island, including details of the Terror Rift (TE-2D). Previous geophysical studies north of Ross Island have determined the north-south trending Terror Rift within the broader Victoria Land Basin, which are part of the intraplate West Antarctic Rift System. For TE-2D, 21 seismic recorders (Ref Tek 130) with three-component 4.5 Hz geophones (Sercel L-28-3D) were deployed along a 77-km east-west line between Capes Royds and Crozier. For TE-3D, 79 similar instruments were deployed in a 3 x 3 km grid around the crater of Erebus, an array of 8 permanent short period and broadband sensors and 23 three-component sensors (Guralp CMG-40T, 30s-100 Hz) were positioned around the flanks and summit of Erebus. Fifteen chemical sources ranging from 75 to 600 kg of ANFO were used. An additional shot was detonated in the sea (McMurdo Sound) using 200 kg of dynamite. Although the station spacing is ~5 km, the data have a high signal to noise ratio with clear first arrivals and wide-angle reflections across the array. Forward modelling ray tracing was used to develop 1-D P-wave velocity models by matching layers of known velocities with the P-wave first arrival times. 1-D velocity models developed for 3 sources and show ~3 layers with a velocity of ~7 km/s below 6-8 km depth. The 1-D models were used as the starting model for a the P-wave tomographic velocity model.

  9. Variability and Trends in Sea Ice Extent and Ice Production in the Ross Sea

    NASA Technical Reports Server (NTRS)

    Comiso, Josefino; Kwok, Ronald; Martin, Seelye; Gordon, Arnold L.

    2011-01-01

    Salt release during sea ice formation in the Ross Sea coastal regions is regarded as a primary forcing for the regional generation of Antarctic Bottom Water. Passive microwave data from November 1978 through 2008 are used to examine the detailed seasonal and interannual characteristics of the sea ice cover of the Ross Sea and the adjacent Bellingshausen and Amundsen seas. For this period the sea ice extent in the Ross Sea shows the greatest increase of all the Antarctic seas. Variability in the ice cover in these regions is linked to changes in the Southern Annular Mode and secondarily to the Antarctic Circumpolar Wave. Over the Ross Sea shelf, analysis of sea ice drift data from 1992 to 2008 yields a positive rate of increase in the net ice export of about 30,000 sq km/yr. For a characteristic ice thickness of 0.6 m, this yields a volume transport of about 20 cu km/yr, which is almost identical, within error bars, to our estimate of the trend in ice production. The increase in brine rejection in the Ross Shelf Polynya associated with the estimated increase with the ice production, however, is not consistent with the reported Ross Sea salinity decrease. The locally generated sea ice enhancement of Ross Sea salinity may be offset by an increase of relatively low salinity of the water advected into the region from the Amundsen Sea, a consequence of increased precipitation and regional glacial ice melt.

  10. Late Wisconsin and early holocene glacial history, inner Ross Embayment, Antarctica

    NASA Technical Reports Server (NTRS)

    Denton, George H.; Bockheim, James G.; Wilson, Scott C.; Stuiver, Minze

    1991-01-01

    Lateral drift sheets of outlet glaciers that pass through the Transantarctic Mountains constrain past changes of the huge Ross ice drainage system of the Antarctic Ice Sheet. Drift stratigraphy suggests correlation of Reedy III (Reedy Glacier), Beardmore, Britannia (Hatherton/Darwin Glaciers), Ross Sea (McMurdo Sound), and younger (Terra Nova Bay) drifts; radiocarbon dates place the outer limits of Ross Sea drift in late Wisconsin time at 24,000 to 13,000 yr B.P. Outlet glacier profiles from these drifts constrain late Wisconsin ice sheet surface elevations. Within these constraint, two extreme late Wisconsin reconstructions are given of the Ross ice drainage system. Both show little elevation change of the polar plateau coincident with extensive ice shelf grounding along the inner Ross Embayment. However, in the central Ross Embayment, one reconstruction shows floating shelf ice, where as the other shows a grounded ice sheet. Massive late Wisconsin/Holocene recession of grounded ice from the western Ross Embayment, which was underway at 13,040 yr B.P. and completed by 6600 to 6020 yr B.P., was accompanied by little change in plateau ice levels inland of the Transantarctic Mountains.

  11. Regional seismic stratigraphic correlations of the Ross Sea: Implications for the tectonic history of the West Antarctic Rift System

    USGS Publications Warehouse

    Decesari, Robert C.; Sorlien, Christopher C.; Luyendyk, Bruce P.; Wilson, Douglas S.; Bartek, Louis; Diebold, John; Hopkins, Sarah E.

    2007-01-01

    Using existing and new seismic reflection data, new and updated correlations of late Oligocene-early Miocene RSS-2 strata were made between the southern parts of Ross Sea basins. Previous studies documented Cretaceous extension across much of Ross Sea. We interpret that Cenozoic extension also occurred across Ross Sea. Subsidence during and following this extension deepened existing basins and may have initiated basins in the west, subsiding ridges between basins below sea level during the late Oligocene. Pre-Oligocene strata record cessation of L. Cretaceous extension in easternmost Ross Sea. Successively younger Cenozoic extension occurred from east to west across the rest of Ross Sea.

  12. Ross Sea Till Properties: Implications for Ice Sheet Bed Interaction

    NASA Astrophysics Data System (ADS)

    Halberstadt, A. R.; Anderson, J. B.; Simkins, L.; Prothro, L. O.; Bart, P. J.

    2015-12-01

    Since the discovery of a pervasive shearing till layer underlying Ice Stream B, the scientific community has categorized subglacial diamictons as either deformation till or lodgement till primarily based on shear strength. Deformation till is associated with streaming ice, formed through subglacial deformation of unconsolidated sediments. Lodgement till is believed to be deposited by the plastering of sediment entrained at the base of slow-flowing ice onto a rigid bed. Unfortunately, there has been a paucity of quantitative data on the spatial distribution of shear strength across the continental shelf. Cores collected from the Ross Sea on cruises NBP1502 and NBP9902 provide a rich dataset that can be used to interpret till shear strength variability. Till strengths are analyzed within the context of: (1) geologic substrate; (2) water content and other geotechnical properties; (3) ice sheet retreat history; and (4) geomorphic framework. Tills display a continuum of shear strengths rather than a bimodal distribution, suggesting that shear strength cannot be used to distinguish between lodgement and deformation till. Where the substrate below the LGM unconformity is comprised of older lithified deposits, till shear strengths are both highly variable within the till unit, as well as highly variable between cores. Conversely, where ice streams flowed across unconsolidated Plio-Pleistocene deposits, shear strengths are low and less variable within the unit and between cores. This suggests greater homogenization of cannibalized tills, and possibly a deeper pervasive shear layer. Coarser-grained tills are observed on banks and bank slopes, with finer tills in troughs. Highly variable and more poorly sorted tills are found in close proximity to sediment-based subglacial meltwater channels, attesting to a change in ice-bed interaction as subglacial water increases. Pellets (rounded sedimentary clasts of till matrix) are observed in Ross Sea cores, suggesting a history of

  13. Neogene Development of the Terror Rift, western Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Sauli, C.; Sorlien, C. C.; Busetti, M.; De Santis, L.; Wardell, N.; Henrys, S. A.; Geletti, R.; Wilson, T. J.; Luyendyk, B. P.

    2015-12-01

    Terror Rift is a >300 km-long, 50-70 km-wide, 14 km-deep sedimentary basin at the edge of the West Antarctic Rift System, adjacent to the Transantarctic Mountains. It is cut into the broader Victoria Land Basin (VLB). The VLB experienced 100 km of mid-Cenozoic extension associated with larger sea floor spreading farther north. The post-spreading (Neogene) development of Terror Rift is not well understood, in part because of past use of different stratigraphic age models. We use the new Rossmap seismic stratigraphy correlated to Cape Roberts and Andrill cores in the west and to DSDP cores in the distant East. This stratigraphy, and new fault interpretations, was developed using different resolutions of seismic reflection data included those available from the Seismic Data Library System. Depth conversion used a new 3D velocity model. A 29 Ma horizon is as deep as 8 km in the south, and a 19 Ma horizon is >5 km deep there and 4 km-deep 100 km farther north. There is a shallower northern part of Terror Rift misaligned with the southern basin across a 50 km right double bend. It is bounded by steep N-S faults down-dropping towards the basin axis. Between Cape Roberts and Ross Island, the Oligocene section is also progressively-tilted. This Oligocene section is not imaged within northern Terror Rift, but the simplest hypothesis is that some of the Terror Rift-bounding faults were active at least during Oligocene through Quaternary time. Many faults are normal separation, but some are locally vertical or even reverse-separation in the upper couple of km. However, much of the vertical relief of the strata is due to progressive tilting (horizontal axis rotation) and not by shallow faulting. Along the trend of the basin, the relief alternates between tilting and faulting, with a tilting margin facing a faulted margin across the Rift, forming asymmetric basins. Connecting faults across the basin form an accommodation zone similar to other oblique rifts. The Neogene basin is

  14. Frank Ross's Early Direct Photographs of Venus and His Interpretation of Them

    NASA Astrophysics Data System (ADS)

    Osterbrock, Donald E.

    2006-09-01

    Frank Ross was an outstandingly creative astronomical "jack of many trades" (Monet) or "cat with nine astronomical lives". After joining the Yerkes Observatory faculty in 1924, at age 50, he took a long series of almost nightly direct photographs of Venus in 1927 with the Mount Wilson 60-inch and 100-inch reflectors as a guest observer. He published many of these images in the ApJ in 1928, with his conclusions on the nature of Venus. Ross discovered markings, seen only in the ultraviolet images, parallel "belts" indicating rotation. They changed rapidly. From these photographs he developed a tentative picture of a deep opaque atmosphere, with high pressure at the surface of the planet. The changes were due to "violent events" (winds or storms) in its atmosphere. From spectroscopic results of Slipher, Adams, StJohn, and Nicholson he took the rotation period to be long. But bolometric observations of Pettit, Nicholson, Coblentz, and Lampland, indicated little temperature change between the illuminated and dark parts of the disk, so it could not be too slow. Ross settled on a "compromise" rotation period of about 30 days based on the data he had. The spectroscopic measurements showed there was very little, if any, H2O or O2 in the atmosphere. Ross is best known today for his Ross wide-angle camera design, his Ross high-proper-motion stars, his Ross photometer, and his Ross correctors for large reflecting telescopes, but his foray into planetary astronomy, long before the era of radar or close-up imaging and spectroscopy from space vehicles, was an important first step toward understanding Venus. His years of experience in laboratory studies of the properties of photographic plates, developers, and mensuration were highly important for this work. Equally so were his cheerful, peppery personality and his close relations with many Mount Wilson and Lowell Observatory staff members.

  15. 75 FR 41512 - Draft Environmental Impact Statement/General Management Plan; Ross Lake National Recreation Area...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-16

    ...Pursuant to Sec. 102(2)(C) of the National Environmental Policy Act of 1969 (Pub. L. 91-190, as amended), and the Council on Environmental Quality Regulations (40 CFR part 1500-1508), the National Park Service (NPS), Department of the Interior, has prepared a draft environmental impact statement for the proposed General Management Plan (GMP) for Ross Lake National Recreation Area (Ross Lake......

  16. Quantifying fall migration of Ross's gulls (Rhodostethia rosea) past Point Barrow, Alaska

    USGS Publications Warehouse

    Uher-Koch, Brian D.; Davis, Shanti E.; Maftei, Mark; Gesmundo, Callie; Suydam, R.S.; Mallory, Mark L.

    2014-01-01

    The Ross's gull (Rhodostethia rosea) is a poorly known seabird of the circumpolar Arctic. The only place in the world where Ross's gulls are known to congregate is in the near-shore waters around Point Barrow, Alaska where they undertake an annual passage in late fall. Ross's gulls seen at Point Barrow are presumed to originate from nesting colonies in Siberia, but neither their origin nor their destination has been confirmed. Current estimates of the global population of Ross's gulls are based largely on expert opinion, and the only reliable population estimate is derived from extrapolations from previous counts conducted at Point Barrow, but these data are now over 25 years old. In order to update and clarify the status of this species in Alaska, our study quantified the timing, number, and flight direction of Ross's gulls passing Point Barrow in 2011. We recorded up to two-thirds of the estimated global population of Ross's gulls (≥ 27,000 individuals) over 39 days with numbers peaking on 16 October when we observed over 7,000 birds during a three-hour period.

  17. Ross, Macdonald, and a Theory for the Dynamics and Control of Mosquito-Transmitted Pathogens

    PubMed Central

    Smith, David L.; Battle, Katherine E.; Hay, Simon I.; Barker, Christopher M.; Scott, Thomas W.; McKenzie, F. Ellis

    2012-01-01

    Ronald Ross and George Macdonald are credited with developing a mathematical model of mosquito-borne pathogen transmission. A systematic historical review suggests that several mathematicians and scientists contributed to development of the Ross-Macdonald model over a period of 70 years. Ross developed two different mathematical models, Macdonald a third, and various “Ross-Macdonald” mathematical models exist. Ross-Macdonald models are best defined by a consensus set of assumptions. The mathematical model is just one part of a theory for the dynamics and control of mosquito-transmitted pathogens that also includes epidemiological and entomological concepts and metrics for measuring transmission. All the basic elements of the theory had fallen into place by the end of the Global Malaria Eradication Programme (GMEP, 1955–1969) with the concept of vectorial capacity, methods for measuring key components of transmission by mosquitoes, and a quantitative theory of vector control. The Ross-Macdonald theory has since played a central role in development of research on mosquito-borne pathogen transmission and the development of strategies for mosquito-borne disease prevention. PMID:22496640

  18. Albert Ross Tilley: The legacy of a Canadian plastic surgeon

    PubMed Central

    Mowbrey, Kevin

    2013-01-01

    The present article chronicles the career of Dr Albert Ross Tilley, one of the most important Canadian plastic surgeons of the 20th century. Tilley is most well known for his innovations of burn management during World War II and his treatment of a group of burn patients known affectionately as the ‘Guinea Pig Club’. In addition to the superb surgical skills he applied to the physical wounds of his patients, Tilley was also a pioneer of caring for the emotional and psychological afflictions suffered by many airmen of World War II. As one of the founding fathers of the Canadian Society of Plastic Surgeons, Tilley’s work was instrumental in establishing the specialty and ensured its prosperity for years to come. Serving in the capacity of leader, educator and innovator, Tilley remains one of Canada’s most decorated physicians, and his body of work encompasses contributions to the medical field that remain significant and beneficial to patient care to this day. PMID:24431953

  19. Seasonal circulation under the eastern Ross Ice Shelf, Antarctia

    SciTech Connect

    Hellmer, H.H.; Jacobs, S.S.

    1995-06-15

    An annual cycle of shelf water temperatures and salinities measured at depth near the eastern Ross Ice Shelf front is used to force a two-dimensional thermohaline circulation model adapted to different subice paths in the vicinity of Roosevelt Island. These paths were assumed to have constant water column thicknesses of 160, 200, and 240 m and lengths of 460-800 km. Additional simulations with the longer cavity included a 80-m thick interior water column in order to approximate conditions closer to the grounding line. Model results were compared with other long-term measurements that showed outflow from beneath the ice shelf. Shelf water flowing into the cavity west of Roosevelt Island appears to follow a cyclonic route around the island. The ice shelf base loses mass at a rate of 18-27 cm yr{sup {minus}1}, with seasonal forcing increasing the spatial and temporal variability of circulation and property distributions in the larger cavities. Shallow cavities reduce the influence of shelf water variability with increasing length. Introducing a transient shelf water temperature rise of 0.01{degrees}C yr {sup {minus}1} for 100 years increases the melt rate by 4-5 times. However, this increase is smaller if salinity also decreases over the same period of time, as might be expected from the added meltwater component. 42 refs., 9 figs.

  20. Movement of fuel spills in the Ross Ice Shelf

    SciTech Connect

    Tumeo, M.A.; Larson, M.K.

    1994-12-31

    Williams Field provides logistical support to McMurdo Station in Antarctica and managers large amounts of fuel for their cargo planes. Numerous spills have occurred at this site with little recovery or remediation of the spilled fuel. From 1980 to 1989, approximately 380,000 liters (L) leaked during documented fuel spills-197,600 L of that total came from one spill alone, in October of 1989, when fuel leaked onto the ice at Williams Field. An additional 20 spills of unknown quantities have also occurred at McMurdo Station and Williams Field. Although recent improvements in equipment and procedures in Antarctica have significantly reduced the accidental release of fuel and all but eliminated the risk of a large fuel spill, the potential for small releases still exists. To track the movement of fuel spills on the ice shelf more accurately and to established the basis for remediation methods NSF funded a 3-year study. This article discusses information obtained about the movement of fuel from a small oil spill from a flexible pipeline between McMurdo Station and Williams Field on the Ross Ice Shelf. 1 fig., 1 tab.

  1. Long-term productivity in the cryptoendolithic microbial community of the Ross Desert, Antarctica

    NASA Technical Reports Server (NTRS)

    Friedmann, E. I.; Kappen, L.; Meyer, M. A.; Nienow, J. A.

    1993-01-01

    Annual gross productivity of the lichen-dominated cryptoendolithic community was calculated from a computer analysis of photosynthetic response based on laboratory measurements of CO2 exchange and three years (1985-1988) of field nanoclimate data. Photosynthetic optimum increased from -3 to 2 degrees C between irradiance levels of 100 and 1500 micromoles photons m-2 s-1, while the upper compensation point rose from 1 to 17 degrees C. The mean yearly total time available for metabolic activity (temperature above -10 degrees C and moisture present) was 771.3 h for horizontal rock, 421.5 h for northeast-oriented sloped rock, and 1042.2 h for a small depression in horizontal rock (the characteristic site of occasional lichen apothecia). The calculated mean gross productivity value for a horizontal rock was 1215 mg C m-2 y-1, and net photosynthetic gain was 606 mg C m-2 y-1. Net ecosystem productivity (annual accretion of cellular biomass) estimated from long-term events amounted to only about 3 mg C m-2 y-1. The difference between these two values may represent the long-term metabolic costs of the frequent dehydration-rehydration and freezing-thawing cycles or of overwintering, and may account for the leaching of organic substances to the rock. The yearly gross productivity of the cryptoendolithic microbial community of the entire Ross Desert area was estimated at approximately 120,000-180,000 kg C. Of this, 600-900 kg C is in microbial biomass, and much of the rest is soluble compounds that leach into the rocks and possibly percolate to the valleys, providing a source of organic matter for lakes, rivers, and soils.

  2. Antarctic marine ice sheet retreat in the Ross Sea during the early Holocene

    NASA Astrophysics Data System (ADS)

    Mckay, R. M.; Golledge, N.; Naish, T.; Maas, S.; Levy, R. H.; Kuhn, G.; Lee, J. I.; Dunbar, G. B.

    2015-12-01

    Geological constraints on the timing of the retreat of the Last Glacial Maximum (LGM) Antarctic Ice Sheets provide critical insights into the processes controlling marine-based ice sheet stability. The over-deepened, seaward shallowing bathymetry of Antarctica's continental shelves is ideally configured to promote past, and potentially future, marine ice-sheet instability. The retreat history of the LGM ice sheet in the Ross Sea region is primarily constrained by C-14 ages on coastal beach ridges and relict penguin colonies along the Transantarctic Mountain front in the Western Ross Sea. Although these terrestrial sites offer more reliable dates than imprecise C-14 chronologies derived from bulk marine sediments, they may reflect retreat of local piedmont glaciers derived from East Antarctic outlet glaciers rather than representing the timing of retreat of the ice sheet in the central Ross Embayment. We present a sedimentary facies succession and foraminifera-based C-14 chronology from a core collected beneath the Ross Ice Shelf via a hot water drill access hole used for the ANDRILL Coulman High site survey. The site is to the east of Ross Island and distal from the coast, and yields a minimum age for glacial retreat that is approximately 1000 yrs earlier than suggested by coastal records along the nearby Victoria Land coast. We examine the implications of this constraint on the timing of ice sheet retreat in the context of model simulations and new multi-beam bathymetry data acquired in the Western Ross Sea. On the basis of these data we hypothesize that marine-based ice sheet retreat was triggered by oceanic forcings along most of the Pacific Ocean coastline of Antarctica simultaneously, but continued retreat in the Ross Sea occurred primarily as a consequence of marine ice sheet instability.

  3. Correlating flexural moat subsidence with grounding line fluctuations around Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Jha, S.; Harry, D. L.; Wenman, C. P.

    2014-12-01

    The southern Ross Sea basin in West Antarctica has been filled up with a complex sedimentary sequence since ~5 Ma containing a mixture of glacial and glacio-marine strata and flexural basin infill. These strata record past climatically influenced advances and retreats of the West Antarctic Ice Sheet and the volcanic loading history of Ross Island. We hypothesize that the amplitude of flexural uplift of the seafloor caused by volcanic loading on Ross Island was sufficient to cause fluctuations of the ice grounding line position, creating false positives in the climate change interpretations derived from the nearby ANDRILL AND-1B core data. To test this hypothesis, we model flexural deformation and subsidence due to individual volcanic loading episodes on Ross Island. We constrain this model by three seismic horizons (Rsb1, Rsb2, and Rsb3) imaged on seismic profile NBP0401-126m, which trends radially away from Ross Island and across its flexural moat. The horizons bound wedge shaped strata filling the moat during flexural depositional episodes, and range in depth (age) from 146 m-153 m (~2.1 Ma), 282 m-308 m (~3.0 Ma) and 432 m- 463 m (4.3 ± 0.3 Ma) respectively. Our flexure model suggests that AND-1B lies in the flexural moat of the Ross Island flexure basin. Horizons Rsb2 and Rsb3 record the flexural subsidence of the basin during Mt. Bird volcanic loading on Ross Island. Rsb2 and RSb3 correlate with upward changes from diamictites to diatomites and mudstones in the AND-1B stratigraphic record. This lithological change has been interpreted to represent a change from grounded ice to open marine conditions, and a shift in the ice sheet grounding line position. Therefore, our results suggest that the magnitude of flexural subsidence in the flexural moat was sufficient to cause changes from grounded to floating ice at the AND-1B.

  4. The vascular plant flora of Hopewell Culture National Historical Park. Ross County, Ohio

    USGS Publications Warehouse

    Bennett, J.P.; Course, J.E.

    1996-01-01

    HopewellCulture National Historical Park, a unit of the United States National Park Service located in Ross County in south central Ohio, was created to restore, protect, and interpret the legacy of the mound building Hopewell prehistoric peoples. The vascular flora of the park had been estimated to be only 20% known prior to the undertaking of this project. During the spring, summer, and fall of 1995, almost 700 plant specimens were collected by three investigators from five units of the park. Totals of 438 species, 281 genera, and 93 families of vascular plants were discovered, representing 40% of the flora of Ross County, and 17% of the flora of Ohio. Introduced species constituted 32% of the flora. Sixty-five species are new records for Ross County. Two species of special concern, Spiranthes ovalis and Eleocharis ovata, are on the state's threatened and endangered species list. The Hopewell unit had the highest plant diversity of the five units.

  5. ‘Bellography’: Life and Contributions of Ross and Joyce Bell, two New England Naturalists

    PubMed Central

    Spence, John R.; Ball, George E.; Davidson, Robert L.; Rykken, Jessica J.

    2011-01-01

    Abstract The lives and contributions of Ross and Joyce Bell are described with particular attention to studies of invertebrate natural history in the state of Vermont and carabid beetles of several groups, including the world rhysodine fauna. Their work, all done at the University of Vermont, was mainly taxonomic in nature and included aspects of the biology of the species considered. During their careers they described more than 75% of the c. 340 rhysodine species known to science. Ross Bell also wrote a number of seminal papers about the basal relationships of the Adephaga and the comparative anatomy of carabid coxal cavities. Ross and Joyce inspired several generations of students at UVM to take up advanced work in entomology and natural history. PMID:22371660

  6. The M51 mystery: Lord Rosse, Robinson, South and the discovery of spiral structure in 1845

    NASA Astrophysics Data System (ADS)

    Steinicke, Wolfgang

    2012-03-01

    In April 1845 Lord Rosse discovered the spiral structure of M51 with his 72-inch reflector at Birr Castle. Already in March the new telescope had been pointed at the object in Canes Venatici, later nicknamed the 'Whirlpool Nebula'. Two experienced astronomers were present: Sir James South and the Reverend Thomas Romney Robin-son. The problem is that there is no record that they noticed the spiral structure, even though it was immediately seen by Lord Rosse the next month. The solution presented here is based on evidentiary facts, highlighting the nineteenth century astronomical praxis. Focal points are bias, fantasy and a sometimes fatal conspiracy of eye and brain.

  7. Holocene elephant seal distribution implies warmer-than-present climate in the Ross Sea

    PubMed Central

    Hall, B. L.; Hoelzel, A. R.; Baroni, C.; Denton, G. H.; Le Boeuf, B. J.; Overturf, B.; Töpf, A. L.

    2006-01-01

    We show that southern elephant seal (Mirounga leonina) colonies existed proximate to the Ross Ice Shelf during the Holocene, well south of their core sub-Antarctic breeding and molting grounds. We propose that this was due to warming (including a previously unrecognized period from ≈1,100 to 2,300 14C yr B.P.) that decreased coastal sea ice and allowed penetration of warmer-than-present climate conditions into the Ross Embayment. If, as proposed in the literature, the ice shelf survived this period, it would have been exposed to environments substantially warmer than present. PMID:16801535

  8. Sea ice and oceanic processes on the Ross Sea continental shelf

    NASA Technical Reports Server (NTRS)

    Jacobs, S. S.; Comiso, J. C.

    1989-01-01

    The spatial and temporal variability of Antarctic sea ice concentrations on the Ross Sea continental shelf have been investigated in relation to oceanic and atmospheric forcing. Sea ice data were derived from Nimbus 7 scanning multichannel microwave radiometer (SMMR) brightness temperatures from 1979-1986. Ice cover over the shelf was persistently lower than above the adjacent deep ocean, averaging 86 percent during winter with little month-to-month of interannual variability. The large spring Ross Sea polynya on the western shelf results in a longer period of summer insolation, greater surface layer heat storage, and later ice formation in that region the following autumn.

  9. Surgical repair of aortic dissection 16 years post-Ross procedure

    PubMed Central

    Myers, Mollie R.; Magruder, J. Trent; Crawford, Todd C.; Grimm, Joshua C.; Halushka, Marc K.; Baumgartner, William A.; Cameron, Duke E.

    2016-01-01

    The Ross procedure is an excellent choice for younger patients in need of aortic valve replacement. While patients have benefited from superior survival rates associated with this procedure, complications related to aortic root dilatation and degeneration of the autograft may be encountered later in life. These challenges may be exacerbated in those with underlying connective tissue abnormalities, a phenomenon commonly observed in the bicuspid aortic valve population. In this report, we present the case of a patient who presented with an aortic dissection 16 years after a Ross procedure for aortic insufficiency in the setting of a bicuspid aortic valve, and review the existing literature related to this adverse event. PMID:27141044

  10. Surgical repair of aortic dissection 16 years post-Ross procedure.

    PubMed

    Myers, Mollie R; Magruder, J Trent; Crawford, Todd C; Grimm, Joshua C; Halushka, Marc K; Baumgartner, William A; Cameron, Duke E

    2016-01-01

    The Ross procedure is an excellent choice for younger patients in need of aortic valve replacement. While patients have benefited from superior survival rates associated with this procedure, complications related to aortic root dilatation and degeneration of the autograft may be encountered later in life. These challenges may be exacerbated in those with underlying connective tissue abnormalities, a phenomenon commonly observed in the bicuspid aortic valve population. In this report, we present the case of a patient who presented with an aortic dissection 16 years after a Ross procedure for aortic insufficiency in the setting of a bicuspid aortic valve, and review the existing literature related to this adverse event. PMID:27141044

  11. Barometric effects on tabular iceberg drift in the Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Turnbull, Ian D.

    The Inverse Barometer Effect (IBE) was observed in the nineteenth century by Sir James Clark Ross (Ross, 1854a), as deviations in sea-surface elevation in response to deviations in atmospheric pressure. This effect embodies the inverse relationship between sea-surface height (relative to long-term mean sea level) and atmospheric surface pressure. This thesis addresses the hypothesis that icebergs in the Ross Sea region of Antarctica are influenced by the same forces that create the IBE. This hypothesis is motivated by studies of icebergs in the Ross Sea, where drift data suggest that icebergs are drawn into temporary holding zones, or "Iceberg Parking Lots" situated where the surface pressure tends to display persistent, annual average low pressure. A physical explanation for the IBE's influence on icebergs is that they are often able to travel up the sea-surface slope induced by the IBE below atmospheric lows against the gravitational pull because of the pressure gradient force of the atmosphere acting on the iceberg's freeboard (the part of the iceberg that is above the waterline). Here, I evaluate the validity of the hypothesized IBE-iceberg relationship using a combined approach of data analysis and modeling. I have examined atmospheric surface pressure and wind records taken directly from the surfaces of four Ross Sea icebergs---B15A, B15K, C16, and B15J, and I have also built, and experimented with, models that predict iceberg drift response to atmospheric surface pressure and surface winds, using observed pressures and winds from B15A and B15J as model forcing. I additionally performed various experiments on a large, idealized tabular iceberg's physical sensitivity to the IBE using a model that treats atmospheric pressure and winds in an idealized, theoretical manner. I discovered that the IBE is indeed a significant influence on iceberg drift in and around Lewis Bay, just to the north of Ross Island, which will further our understanding of these icebergs

  12. Holocene elephant seal distribution implies warmer-than-present climate in the Ross Sea.

    PubMed

    Hall, B L; Hoelzel, A R; Baroni, C; Denton, G H; Le Boeuf, B J; Overturf, B; Töpf, A L

    2006-07-01

    We show that southern elephant seal (Mirounga leonina) colonies existed proximate to the Ross Ice Shelf during the Holocene, well south of their core sub-Antarctic breeding and molting grounds. We propose that this was due to warming (including a previously unrecognized period from approximately 1,100 to 2,300 (14)C yr B.P.) that decreased coastal sea ice and allowed penetration of warmer-than-present climate conditions into the Ross Embayment. If, as proposed in the literature, the ice shelf survived this period, it would have been exposed to environments substantially warmer than present. PMID:16801535

  13. STS-37 Mission Specialist (MS) Ross during simulation in JSC's FB-SMS

    NASA Technical Reports Server (NTRS)

    1991-01-01

    STS-37 Mission Specialist (MS) Jerry L. Ross 'borrows' the pilots station to rehearse some of his scheduled duties for his upcoming mission. He is on the flight deck of the fixed-based (FB) shuttle mission simulator (SMS) during this unsuited simulation. The SMS is part of JSC's Mission Simulation and Training Facility Bldg 5.

  14. A Helping Hand in the Frederick Community—Ross Smith | Poster

    Cancer.gov

    By day, Ross Smith is the compliance and security officer for Data Management Services, Inc., assigned to the National Cancer Institute (NCI) at Frederick. His role is to ensure the secure operation of in-house computer systems, servers, and network connections. But in his spare time, Smith is also a volunteer firefighter and emergency medical technician (EMT).

  15. California State Waters Map Series—Offshore of Fort Ross, California

    USGS Publications Warehouse

    Johnson, Samuel Y.; Dartnell, Peter; Golden, Nadine E.; Hartwell, Stephen R,; Erdey, Mercedes D.; Greene, H. Gary; Cochrane, Guy R.; Kvitek, Rikk G.; Manson, Michael W.; Endris, Charles A.; Dieter, Bryan E.; Watt, Janet T.; Krigsman, Lisa M.; Sliter, Ray W.; Lowe, Erik N.; Chin, John L.

    2015-01-01

    Potential marine benthic habitat types in the Offshore of Fort Ross map area include unconsolidated continental-shelf sediments, mixed continental-shelf substrate, and hard continental-shelf substrate. Rocky shelf outcrops and rubble are considered the primary habitat type for rockfish and lingcod, both of which are recreationally and commercially important species.

  16. Photographer: Digital Telepresence: Dr Murial Ross's Virtual Reality Application for Neuroscience

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Photographer: Digital Telepresence: Dr Murial Ross's Virtual Reality Application for Neuroscience Research Biocomputation. To study human disorders of balance and space motion sickness. Shown here is a 3D reconstruction of a nerve ending in inner ear, nature's wiring of balance organs.

  17. Two Case Histories, Ishbel Ross and Emma Bugbee: Women Journalists Ride the Rail with the Suffragettes.

    ERIC Educational Resources Information Center

    Merrick, Beverly G.

    The rise to prominence of the women's suffrage movement in the World War I years brought women reporters into U.S. newsrooms for the first time. In 1911 Emma Bugbee became the first woman hired as a "hard" news reporter for the "New York Tribune" (later the "Herald Tribune"). Ishbel Ross, author of "Ladies of the Press," got her start in…

  18. A GENETIC COMPONENT TO THE NORMAL GROWTH OF THE ROSS 708 BROILER CHICKEN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A growth trial was conducted with the Ross 708 broiler chicken to corroborate the relationships between changes in the growth curve (7 to 35 days) and in vitro metabolic parameters. These in vitro parameters also included estimates of the expression of certain genes regulating proteins implicated wi...

  19. Phytoplankton taxonomic variability in nutrient utilization and primary production in the Ross Sea

    NASA Astrophysics Data System (ADS)

    Arrigo, Kevin R.; DiTullio, Giacomo R.; Dunbar, Robert B.; Robinson, Dale H.; VanWoert, Michael; Worthen, Denise L.; Lizotte, Michael P.

    2000-04-01

    Patterns of nutrient utilization and primary productivity (PP) in late austral spring and early summer in the southwestern Ross Sea were characterized with respect to phytoplankton taxonomic composition, polynya dynamics, and upper ocean hydrography during the 1996-1997 oceanographic program Research on Ocean-Atmosphere Variability and Ecosystem Response in the Ross Sea. Phytoplankton biomass in the upper 150 m of the water column ranged from 40 to 540 mg chlorophyll a (Chl a) m-2, exceeding 200 mg Chl a m-2 everywhere except the extreme northern and eastern boundaries of the Ross Sea polynya. Diatom biomass was greatest in the shallow mixed layers of Terra Nova Bay, while the more deeply mixed waters of the Ross Sea polynya were dominated by Phaeocystis antarctica. Daily production computed from the disappearance of NO3(1.14gCm-2d-1) and total dissolved inorganic carbon (TDIC, 1.29 g C m-2 d-1) is consistent with estimates made from an algorithm forced with satellite measurements of Chl a (1.25 g C m-2 d-1) and from measurements of 14C uptake (1.33 g C m-2 d-1). Phytoplankton PP in the Ross Sea averaged 100 g C m-2 yr-1 during 1996-1997. Despite the early formation of the Terra Nova Bay polynya the diatom bloom there did not reach its peak PP until middle to late January 1997 (most likely because of more intense wind mixing in November), ~6 weeks after the P. antarctica bloom in the Ross Sea polynya had reached the same stage of development. From 70 to 100% of the C and N deficits in the upper 150 m could be accounted for by particulate organic matter, indicating that there had been little dissolved organic matter production or export of particulate material prior to our cruise. This suggests that early in the season, PP and zooplankton grazing are decoupled in the southwestern Ross Sea. The NO3:PO4 disappearance ratio in waters dominated by P. antarctica (19.0+/-0.61) was significantly greater than in waters where diatoms were most common (9.52+/-0.33), and both

  20. Crustal Vp-Vs ratios and thickness for Ross Island and the Transantarctic Mountain front, Antarctica

    NASA Astrophysics Data System (ADS)

    Finotello, Marco; Nyblade, Andrew; Julia, Jordi; Wiens, Douglas; Anandakrishnan, Sridhar

    2011-04-01

    We investigate crustal Vp-Vs ratios and thickness along the Transantarctic Mountain (TAM) front and on Ross Island, Antarctica to determine if the TAM crust has been modified by the Neogene magmatism associated with Ross Island. A seismic low velocity zone (LVZ) in the upper mantle beneath Ross Island extends laterally ˜80 km under the TAM front, and mantle temperatures within the LVZ may be sufficiently elevated for partial melting to have occurred and modified the crust. Data for the study come from 16 temporary seismic stations that were part of the TAM Seismic Experiment and three permanent stations. Estimates of Vp/Vs (κ) and crustal thickness (H) have been obtained from receiver functions analysed using the H-κ stacking method for 10 of the stations, and for the remaining stations, crustal thickness has been calculated by using the Moho Ps arrival time with an assumed Vp/Vs value. A Vp/Vs value of 1.88 is obtained for Ross Island, consistent with the mafic composition of the volcanic rocks from Mt. Erebus. Vp/Vs values for stations in the TAM situated away from the LVZ range from 1.63 to 1.78, with a mean of 1.73, while values for stations in the TAM lying above the LVZ range from 1.67 to 1.78, with a mean of 1.72. This result indicates that there is little difference in bulk crustal composition for areas above and away from the LVZ, and together with a Vp/Vs value (1.73) that is typical for felsic to intermediate composition crust, suggests that the crust along the TAM front has not been altered significantly by mafic magmatism. Crustal thickness estimates along the coast are quite variable, ranging from 18 to 33 km, and increase to 39 km inland beneath the crest of the TAM. On Ross Island, crustal thickness estimates range between 19 and 27 km.

  1. Pleistocene variability of Antarctic Ice Sheet extent in the Ross Embayment

    NASA Astrophysics Data System (ADS)

    McKay, Robert; Naish, Tim; Powell, Ross; Barrett, Peter; Scherer, Reed; Talarico, Franco; Kyle, Philip; Monien, Donata; Kuhn, Gerhard; Jackolski, Chris; Williams, Trevor

    2012-02-01

    Cores acquired by the ANDRILL McMurdo Ice Shelf Project (AND-1B) provide the basis for a new sedimentation model for glacimarine depositional sequences that reflect cyclic glacial-interglacial fluctuations of a marine-based ice sheet in the western Ross Embayment over the past 2.0 Ma. Notwithstanding periodic erosion during advances of the ice sheet, uncertainties inherent to the sedimentological interpretation, and a limited number of chronological datums, it is clear that subglacial to grounding-zone sedimentation was dominant at the AND-1B site during the Late Pleistocene with interglacials being represented only by thin intervals of ice-shelf sediment. Each sequence is characterised by subglacial, massive diamictite that pass upwards into glacimarine diamictites and mudstones. This provides the first direct evidence that the marine-based Antarctic Ice Sheet has oscillated between a grounded and floating state at least 7 times in the Ross Embayment over the last 780ka, implying a Milankovitch orbital influence. An unconformity in AND-1B, that spans most (˜200 kyr) of the Mid-Pleistocene Transition is inferred to represent widespread expansion of a marine-based ice sheet in the Ross Embayment at 0.8 Ma. Prior to 1.0 Ma, interglacial periods are characterised by open-water conditions at the drill site with high abundances of volcanoclastic deposits and occasional diatomaceous sediments. These may have responded to precession (˜20-kyr) or obliquity (˜40-kyr) orbital control. The occurrence of 6.7 m of phonolitic glass reworked from Mt Erebus in interglacial deposits beneath Last Glacial Maximum till requires open ocean or ice shelf conditions in the western Ross Sea around the drill site within the past 250 ka and implies a Ross Ice Shelf similar to or less extensive than today during Marine Isotope Stage 7 or 5.

  2. Flexural Rigidity Around Ross Island, Antarctica Based On Geodynamic Modeling And Seismic Stratigraphy

    NASA Astrophysics Data System (ADS)

    Jha, S.; Witt, D. R.; Harry, D. L.

    2013-12-01

    Quantifying the flexural subsidence history around Mt. Erebus, located on Ross Island in the southern Ross Sea of West Antarctica, is essential to separating the tectonic, volcanic, and climatic signals in the stratigraphic record contained in regional seismic reflection and borehole data. Toward this end, we analyze both broken and continuous plate models of flexural subsidence due to volcanic loading around Mt. Erebus. Seismic reflection data from the IT90AR71, NBP0401-118m and NBP0401-126m seismic surveys are used to identify stratigraphic horizons associated with loading during different eruptive events. Based on results obtained by ANTOSTRAT, we have identified 5 seismic horizons RSb1 (early Oligocene), RSb2 (late Oligocene to early Miocene), RSb3 (early Miocene), RSb4(early to middle Miocene) and RSb5 (middle Miocene), which are correlated with the CIROS-1 drill hole, in the Eastern Ross Sea to identify 5 episodes of flexural subsidence related to Ross Island volcanic loading. The seismic data indicate that the flexural bulge associated with all 5 volcanic loading events is located at an average distance of 250 km from Mt. Erebus. We use the position of the flexural bulge and the dip of strata within the basin to constrain geodynamic models of flexural subsidence due to volcanic loading. We assume a mantle density of 3200 kg/m^3 and density of sedimentary basin infill of 2700 kg/m^3. Our preliminary results suggest that a broken plate, point load model is the most ideal case for Ross Island. The flexural rigidity is approximately 10^22.5 N-m, and the cumulative load of all volcanic episodes of Mt. Erebus is 9x10^11 N.

  3. Widespread collapse of the Ross Ice Shelf during the late Holocene.

    PubMed

    Yokoyama, Yusuke; Anderson, John B; Yamane, Masako; Simkins, Lauren M; Miyairi, Yosuke; Yamazaki, Takahiro; Koizumi, Mamito; Suga, Hisami; Kusahara, Kazuya; Prothro, Lindsay; Hasumi, Hiroyasu; Southon, John R; Ohkouchi, Naohiko

    2016-03-01

    The stability of modern ice shelves is threatened by atmospheric and oceanic warming. The geologic record of formerly glaciated continental shelves provides a window into the past of how ice shelves responded to a warming climate. Fields of deep (-560 m), linear iceberg furrows on the outer, western Ross Sea continental shelf record an early post-Last Glacial Maximum episode of ice-shelf collapse that was followed by continuous retreat of the grounding line for ∼200 km. Runaway grounding line conditions culminated once the ice became pinned on shallow banks in the western Ross Sea. This early episode of ice-shelf collapse is not observed in the eastern Ross Sea, where more episodic grounding line retreat took place. More widespread (∼280,000 km(2)) retreat of the ancestral Ross Ice Shelf occurred during the late Holocene. This event is recorded in sediment cores by a shift from terrigenous glacimarine mud to diatomaceous open-marine sediment as well as an increase in radiogenic beryllium ((10)Be) concentrations. The timing of ice-shelf breakup is constrained by compound specific radiocarbon ages, the first application of this technique systematically applied to Antarctic marine sediments. Breakup initiated around 5 ka, with the ice shelf reaching its current configuration ∼1.5 ka. In the eastern Ross Sea, the ice shelf retreated up to 100 km in about a thousand years. Three-dimensional thermodynamic ice-shelf/ocean modeling results and comparison with ice-core records indicate that ice-shelf breakup resulted from combined atmospheric warming and warm ocean currents impinging onto the continental shelf. PMID:26884201

  4. Widespread collapse of the Ross Ice Shelf during the late Holocene

    PubMed Central

    Yokoyama, Yusuke; Anderson, John B.; Yamane, Masako; Simkins, Lauren M.; Miyairi, Yosuke; Yamazaki, Takahiro; Koizumi, Mamito; Suga, Hisami; Kusahara, Kazuya; Prothro, Lindsay; Hasumi, Hiroyasu; Southon, John R.; Ohkouchi, Naohiko

    2016-01-01

    The stability of modern ice shelves is threatened by atmospheric and oceanic warming. The geologic record of formerly glaciated continental shelves provides a window into the past of how ice shelves responded to a warming climate. Fields of deep (−560 m), linear iceberg furrows on the outer, western Ross Sea continental shelf record an early post-Last Glacial Maximum episode of ice-shelf collapse that was followed by continuous retreat of the grounding line for ∼200 km. Runaway grounding line conditions culminated once the ice became pinned on shallow banks in the western Ross Sea. This early episode of ice-shelf collapse is not observed in the eastern Ross Sea, where more episodic grounding line retreat took place. More widespread (∼280,000 km2) retreat of the ancestral Ross Ice Shelf occurred during the late Holocene. This event is recorded in sediment cores by a shift from terrigenous glacimarine mud to diatomaceous open-marine sediment as well as an increase in radiogenic beryllium (10Be) concentrations. The timing of ice-shelf breakup is constrained by compound specific radiocarbon ages, the first application of this technique systematically applied to Antarctic marine sediments. Breakup initiated around 5 ka, with the ice shelf reaching its current configuration ∼1.5 ka. In the eastern Ross Sea, the ice shelf retreated up to 100 km in about a thousand years. Three-dimensional thermodynamic ice-shelf/ocean modeling results and comparison with ice-core records indicate that ice-shelf breakup resulted from combined atmospheric warming and warm ocean currents impinging onto the continental shelf. PMID:26884201

  5. Use of supplemental food by breeding Ross's Geese and Lesser Snow Geese: Evidence for variable anorexia

    USGS Publications Warehouse

    Gloutney, M.L.; Alisauskas, R.T.; Hobson, K.A.; Afton, A.D.

    1999-01-01

    Recent research suggests that foods eaten during laying and incubation play a greater role in supplying energy and nutrients to arctic-nesting geese than previously believed. We conducted food-supplementation experiments with Ross's Geese (Chen rossii) and Lesser Snow Geese (C. caerulescens) geese to evaluate: (1) if supplemental food was consumed by laying and incubating geese, (2) how food consumption influenced mass dynamics of somatic tissues of breeding geese, (3) if patterns of mass loss were consistent with fasting adaptations, and (4) whether energetic constraints would cause smaller Ross's Geese to consume more food relative to their body size than would larger Snow Geese. Quantity of supplemental food eaten by both species during laying and incubation was highly variable among individuals. Consumption of supplemental food during laying resulted in differences in overall body composition between control and treatment females. Treatment female Ross's Geese completed laying at a higher mass and with more abdominal fat than controls, whereas treatment female Snow Geese completed laying with heavier breast muscles and hearts. Overall body composition did not differ between control and treatment geese (both sexes and species) at the end of incubation, but treatment geese had heavier hearts than control geese. This suggests that treatment females did not rely to the same extent on metabolic adaptations associated with anorexia to meet energetic costs of incubation as did controls. Stable-nitrogen isotope analysis revealed patterns of protein maintenance during incubation consistent with metabolic adaptations to prolonged fasting. Our prediction that energetic constraints would cause smaller Ross's Geese to consume more food relative to their size than would Snow Geese was not supported. Mass-specific food consumption by Ross's Geese was 30% lower than that of Snow Geese during laying and 48% higher during incubation.

  6. Distribution, density, and abundance of pack-ice seals in the Amundsen and Ross Seas, Antarctica

    NASA Astrophysics Data System (ADS)

    Bengtson, John L.; Laake, Jeff L.; Boveng, Peter L.; Cameron, Michael F.; Bradley Hanson, M.; Stewart, Brent S.

    2011-05-01

    We made three sets of population surveys of the four species of ice-inhabiting phocid pinnipeds in the Ross and Amundsen Seas between 26 December 1999 and 24 March 2000 using icebreakers and helicopters deployed from those icebreakers. We used line transect methods to survey 23,671 km by helicopter and 3,694 km by ship accounting for a total coverage of 53,217 km 2. We detected and identified 11,308 seals in 7,104 groups and estimated their abundance from estimates of densities using distance sampling methods and corrections for probability of haul out of seals derived from satellite telemetry of tagged seals. Crabeater seals were most abundant (ca 1.7 million) followed by Weddell seals (330,000), Ross seals (22,600), and leopard seals (15,000). Our estimates of abundance are difficult to directly compare with earlier estimates because of geographic areas covered and by our improvements in survey and analytical methods. Notwithstanding these limitations and with some adjustments for differences in methods, we found that our estimates of abundance for crabeater seals are similar to those from the most recent surveys in the Ross and Amundsen Seas and along the George-Oates Coast. Our estimates for Weddell seals are the first for the broad areas of pack ice that we surveyed in the Ross and Amundsen Seas but indicate that these habitats are ecologically important to this species. Our estimates of abundance of Ross seals were relatively similar to estimates for surveys in these areas in the 1970s and 1980s whereas our estimates of abundance of leopard seals were substantially lower.

  7. The Scientific Papers of William Parsons, Third Earl of Rosse 1800-1867

    NASA Astrophysics Data System (ADS)

    Parsons, William; Parsons, Charles

    2011-11-01

    From the Edinburgh Journal of Science: 1. 1828. Account of a new reflecting telescope; 2. 1828. Account of an apparatus for grinding and polishing the specula of reflecting telescopes; 3. 1830. Account of a series of experiments on the construction of large reflecting telescopes; From the Proceedings of the Royal Irish Academy: 4. 1840. Account of the three-feet telescope T. R. Robinson; 5. 1845. On Lord Rosse's telescope T. R. Robinson; 6. 1848. On Lord Rosse's telescope T. R. Robinson; 7. 1848. Observation of the nebula, Herschel 44 T. R. Robinson; 8. 1848. Contents of an ancient bronze vessel, in the collection of the Earl of Rosse T. R. Robinson; From Reports of the British Association for the Advancement of Science: 9. 1843. Presidential address by the Earl of Rosse; 10. 1844. On the construction of large reflecting telescopes; 11. 1851. Plain specula of silver; 12. 1852. Drawings to illustrate recent observations on nebulae; 13. 1853. First report of the committee … on the physical characteristics of the Moon's surface; 14. 1857. Mechanical science; 15. 1859. Mathematics and physics; From Monthly Notices of the Royal Astronomical Society: 16. 1854. Notes on experiments relative to lunar photography and the construction of reflecting specula; 17. 1866. Description of an equatoreal clock; The Royal Society: 18. 1854. Address of the Rt. Hon. the Earl of Rosse; From the Philosophical Transactions of the Royal Society: 19. 1840. An account of experiments on the reflecting telescope; 20. 1844. Observations on some of the nebulae; 21. 1850. Observations on the nebulae; 22. 1861. On the construction of specula of six-feet aperture, and a selection from the observations of nebulae made with them; 23. 1867. An account of the observations on the great nebula in Orion, made at Birr Castle, with the 3-feet and 6-feet telescopes, between 1848 and 1867; Institution of Naval Architects: 24. 1854-65. A contribution to the history of ironclads.

  8. Mitigating climate change via iron fertilization: Regional simulation of the Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Arrigo, K. R.; Tagliabue, A.

    2003-04-01

    The dynamic 3-dimensional mesoscale model of the Coupled Ice, Atmosphere, and Ocean (CIAO) ecosystem in the southwestern Ross Sea has been used to investigate the interactions between environmental forcing and the production (primary and secondary) and fate of biogenic carbon. Early simulations by CIAO confirmed that in the Ross Sea, which contains the most productive waters in the Southern Ocean, phytoplankton consumed only about two-thirds of the available macronutrients due to the exhaustion of the available Fe. Simulating Fe-fertilization over the entire Ross Sea resulted in a 50% increase in peak phytoplankton abundance and a 30% increase in phosphate and nitrate utilization. This Fe-stimulated phytoplankton bloom reduced surface TCO2 by ~50 µmol kg-1 and pCO2 by as much as 80 µatm. Influx of atmospheric CO2 increased by 1-3 mmol C m-2 yr-1 as a result of the enhanced Fe supply, effectively doubling the rate of air-sea CO2 exchange in the Ross Sea. Because the Ross Sea supports distinct blooms of diatoms and the prymnesiophyte Phaeocystis antarctica, which differ in their nutrient and carbon utilization ratios, CIAO was used to assess the response of these two communities to exogenous Fe additions. It was found that when Fe was added, diatoms were driven to phosphate limitation and P. antarctica to nitrate limitation. Furthermore, the TCO2 content of surface waters dominated by P. antarctica was 15-26% lower than the TCO2 in waters dominated by diatoms, due primarily to the increased capacity of P. antarctica to draw down CO2.

  9. Ross Sea paleo-ice sheet drainage and deglacial history during and since the LGM

    NASA Astrophysics Data System (ADS)

    Anderson, John B.; Conway, Howard; Bart, Philip J.; Witus, Alexandra E.; Greenwood, Sarah L.; McKay, Robert M.; Hall, Brenda L.; Ackert, Robert P.; Licht, Kathy; Jakobsson, Martin; Stone, John O.

    2014-09-01

    Onshore and offshore studies show that an expanded, grounded ice sheet occupied the Ross Sea Embayment during the Last Glacial Maximum (LGM). Results from studies of till provenance and the orientation of geomorphic features on the continental shelf show that more than half of the grounded ice sheet consisted of East Antarctic ice flowing through Transantarctic Mountain (TAM) outlet glaciers; the remainder came from West Antarctica. Terrestrial data indicate little or no thickening in the upper catchment regions in both West and East Antarctica during the LGM. In contrast, evidence from the mouths of the southern and central TAM outlet glaciers indicate surface elevations between 1000 m and 1100 m (above present-day sea level). Farther north along the western margin of the Ross Ice Sheet, surface elevations reached 720 m on Ross Island, and 400 m at Terra Nova Bay. Evidence from Marie Byrd Land at the eastern margin of the ice sheet indicates that the elevation near the present-day grounding line was more than 800 m asl, while at Siple Dome in the central Ross Embayment, the surface elevation was about 950 m asl. Farther north, evidence that the ice sheet was grounded on the middle and the outer continental shelf during the LGM implies that surface elevations had to be at least 100 m above the LGM sea level. The apparent low surface profile and implied low basal shear stress in the central and eastern embayment suggests that although the ice streams may have slowed during the LGM, they remained active. Ice-sheet retreat from the western Ross Embayment during the Holocene is constrained by marine and terrestrial data. Ages from marine sediments suggest that the grounding line had retreated from its LGM outer shelf location only a few tens of kilometer to a location south of Coulman Island by ˜13 ka BP. The ice sheet margin was located in the vicinity of the Drygalski Ice Tongue by ˜11 ka BP, just north of Ross Island by ˜7.8 ka BP, and near Hatherton Glacier by

  10. The Satellite Passive-Microwave Record of Sea Ice in the Ross Sea Since Late 1978

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.

    2009-01-01

    Satellites have provided us with a remarkable ability to monitor many aspects of the globe day-in and day-out and sea ice is one of numerous variables that by now have quite substantial satellite records. Passive-microwave data have been particularly valuable in sea ice monitoring, with a record that extends back to August 1987 on daily basis (for most of the period), to November 1970 on a less complete basis (again for most of the period), and to December 1972 on a less complete basis. For the period since November 1970, Ross Sea sea ice imagery is available at spatial resolution of approximately 25 km. This allows good depictions of the seasonal advance and retreat of the ice cover each year, along with its marked interannual variability. The Ross Sea ice extent typically reaches a minimum of approximately 0.7 x 10(exp 6) square kilometers in February, rising to a maximum of approximately 4.0 x 10(exp 6) square kilometers in September, with much variability among years for both those numbers. The Ross Sea images show clearly the day-by-day activity greatly from year to year. Animations of the data help to highlight the dynamic nature of the Ross Sea ice cover. The satellite data also allow calculation of trends in the ice cover over the period of the satellite record. Using linear least-squares fits, the Ross Sea ice extent increased at an average rate of 12,600 plus or minus 1,800 square kilometers per year between November 1978 and December 2007, with every month exhibiting increased ice extent and the rates of increase ranging from a low of 7,500 plus or minus 5,000 square kilometers per year for the February ice extents to a high of 20,300 plus or minus 6,100 kilometers per year for the October ice extents. On a yearly average basis, for 1979-2007 the Ross Sea ice extent increased at a rate of 4.8 plus or minus 1.6 % per decade. Placing the Ross Sea in the context of the Southern Ocean as a whole, over the November 1978-December 2007 period the Ross Sea had

  11. CLOUDS IN THE COLDEST BROWN DWARFS: FIRE SPECTROSCOPY OF ROSS 458C

    SciTech Connect

    Burgasser, Adam J.; Simcoe, Robert A.; Bochanski, John J.; Saumon, Didier; Mamajek, Eric E.; McMurtry, Craig; Pipher, Judith L.; Forrest, William J.; Cushing, Michael C.; Marley, Mark S.

    2010-12-20

    Condensate clouds are a salient feature of L dwarf atmospheres, but have been assumed to play little role in shaping the spectra of the coldest T-type brown dwarfs. Here we report evidence of condensate opacity in the near-infrared spectrum of the brown dwarf candidate Ross 458C, obtained with the Folded-Port Infrared Echellette (FIRE) spectrograph at the Magellan Telescopes. These data verify the low-temperature nature of this source, indicating a T8 spectral classification, log{sub 10} L{sub bol}/L{sub sun} = -5.62 {+-} 0.03, T{sub eff} = 650 {+-} 25 K, and a mass at or below the deuterium burning limit. The data also reveal enhanced emission at the K band associated with youth (low surface gravity) and supersolar metallicity, reflecting the properties of the Ross 458 system (age = 150-800 Myr, [Fe/H] = +0.2 to +0.3). We present fits of FIRE data for Ross 458C, the T9 dwarf ULAS J133553.45+113005.2, and the blue T7.5 dwarf SDSS J141624.08+134826.7B, to cloudless and cloudy spectral models from Saumon and Marley. For Ross 458C, we confirm a low surface gravity and supersolar metallicity, while the temperature differs depending on the presence (635{sup +25}{sub -35} K) or absence (760{sup +70}{sub -45} K) of cloud extinction. ULAS J1335+1130 and SDSS J1416+1348B have similar temperatures (595{sup +25}{sub -45} K), but distinct surface gravities (log g = 4.0-4.5 cgs versus 5.0-5.5 cgs) and metallicities ([M/H] {approx} +0.2 versus -0.2). In all three cases, cloudy models provide better fits to the spectral data, significantly so for Ross 458C. These results indicate that clouds are an important opacity source in the spectra of young cold T dwarfs and should be considered when characterizing planetary-mass objects in young clusters and directly imaged exoplanets. The characteristics of Ross 458C suggest that it could itself be regarded as a planet, albeit one whose cosmogony does not conform with current planet formation theories.

  12. Comparison of Ross` capillary barrier diversion formula with detailed numerical simulations

    SciTech Connect

    Webb, S.W.

    1997-04-01

    Ross developed an analytical relationship to calculate the diversion length of a tilted fine-over-coarse capillary barrier. Oldenburg and Pruess compared simulation results using upstream and harmonic weighting to the diversion length predicted by Ross formula with mixed results; the qualitative agreement is reasonable but the quantitative comparison is poor, especially for upstream weighting. The proximity of the water table to the fine-coarse interface at breakthrough is a possible reason for the poor agreement. In the present study, the Oldenburg and Pruess problem is extended to address the water table issue. When the water table is sufficiently far away from the interface at breakthrough, good qualitative and quantitative agreement is obtained using upstream weighting.

  13. ACCURACY OF ROSS PH COMBINATION ELECTRODES IN DILUTE SULPHURIC ACID STANDARDS

    EPA Science Inventory

    The mean observed pH of a 5.00 plus or minus 0.05 x 0.00001 M H2504 solution was 4.06 plus or minus 0.05 (2s) for 485 pH measurements by seven different operators, using nine Orion Ross Model 81-94b pH combination electrodes and four different pH meters over 8 weeks. Traditional ...

  14. Enumeration of Thermophilic Heterotrophs in Geothermally Heated Soils from Mount Erebus, Ross Island, Antarctica

    PubMed Central

    Hudson, J. Andrew; Daniel, Roy M.

    1988-01-01

    Soil samples with temperatures up to 64°C were collected from Mount Erebus, an active volcano located on Ross Island, Antarctica. Acridine orange direct counts and most probable number counts of soil samples stored at 4°C for 2 months showed a wide variation in the number of thermophilic microorganisms in different soils. Organisms similar to Clostridium thermohydrosulfuricum, Bacillus schlegelii, and Bacillus acidocaldarius, as well as neutrophilic Bacillus strains, were isolated. PMID:16347573

  15. Enumeration of thermophilic heterotrophs in geothermally heated soils from mount erebus, ross island, antarctica.

    PubMed

    Hudson, J A; Daniel, R M

    1988-02-01

    Soil samples with temperatures up to 64 degrees C were collected from Mount Erebus, an active volcano located on Ross Island, Antarctica. Acridine orange direct counts and most probable number counts of soil samples stored at 4 degrees C for 2 months showed a wide variation in the number of thermophilic microorganisms in different soils. Organisms similar to Clostridium thermohydrosulfuricum, Bacillus schlegelii, and Bacillus acidocaldarius, as well as neutrophilic Bacillus strains, were isolated. PMID:16347573

  16. Ross Syndrome: A Case Report and Review of Cases from India.

    PubMed

    Agarwala, Manoj Kumar; George, Leni; Parmar, Harshad; Mathew, Vivek

    2016-01-01

    Ross syndrome is a rare dysautonomia characterized by a clinical complex of segmental anhidrosis or hypohidrosis, areflexia, and tonic pupils. A very few cases (≃50) have been reported in literature since its original description in 1958. Here, we report the case of a middle-aged homemaker from Odisha, India, who presented with complaints of segmental hypohidrosis for the past 7 years. PMID:27293279

  17. Modified Stumper technique for acute postoperative bifurcation stenosis causing right ventricular failure after Ross procedure

    PubMed Central

    Divekar, Abhay A

    2016-01-01

    In this report, we describe a 15-year-old patient who underwent a Ross procedure for a regurgitant bicuspid aortic valve and ascending aortic dilation. After the operation was over, he could not be separated from cardiopulmonary bypass and was noted to have isolated right ventricular failure. This report takes the reader through the diagnostic evaluation, highlights the importance of invasive assessment in the immediate postoperative period, and discusses successful transcatheter intervention in the acute postoperative setting. PMID:27625524

  18. Ross Syndrome: A Case Report and Review of Cases from India

    PubMed Central

    Agarwala, Manoj Kumar; George, Leni; Parmar, Harshad; Mathew, Vivek

    2016-01-01

    Ross syndrome is a rare dysautonomia characterized by a clinical complex of segmental anhidrosis or hypohidrosis, areflexia, and tonic pupils. A very few cases (≃50) have been reported in literature since its original description in 1958. Here, we report the case of a middle-aged homemaker from Odisha, India, who presented with complaints of segmental hypohidrosis for the past 7 years. PMID:27293279

  19. Clouds On A Cold Planet: FIRE Spectroscopy Of Ross 458C

    NASA Astrophysics Data System (ADS)

    Burgasser, Adam J.; Simcoe, R. A.; Bochanski, J. J.; Saumon, D.; Mamajek, E. E.; Cushing, M. C.; Marley, M. S.; McMurtry, C.; Pipher, J. L.; Forrest, W. J.

    2011-01-01

    Ross 458C is a widely-separated (1100 AU), faint companion to the nearby M0.5 Ve + M7 Ross 458AB binary, identified in the UKIDSS survey by Goldman et al. and Scholz and suspected by both of being a young brown dwarf. We obtained near-infrared spectroscopy of this source with the newly-commissioned Folded-Port Infrared Echellette (FIRE) at the Magellan Telescopes, which revealed the presence of strong methane and water absorption consistent with a T8 dwarf. The age of this system (150-800 Myr) and the low luminosity of the companion (log Lbol/Lsun = -5.62±0.03) indicate a mass at or below the deuterium burning limit. This is verified through atmospheric model fits to the spectral data, which indicate a low temperature (635 [+25,-35] K), a low surface gravity (log g 4 cgs) and a model-dependent mass of <=6 Jupiter masses. The spectral models further indicate that condensate clouds are present in the atmosphere of Ross 458C, in contrast to results for other cold T dwarfs. These results provide further evidence that clouds are an important opacity source in the spectra of young substellar objects, from planetary-mass brown dwarfs in young clusters to directly-imaged exoplanets. Moreover, its low mass, cool atmosphere and physical association with a stellar system give Ross 458C all of the trappings of a planet, albeit one whose cosmogony may not conform with current planet formation theories. This result includes data gathered with the 6.5-m Magellan Telescopes located at Las Campanas Observatory, Chile. Support for the modeling work of D.S. was provided by NASA through the Spitzer Science Center.

  20. Lesser snow geese and ross's geese form mixed flocks during winter but differ in family maintenance and social status

    USGS Publications Warehouse

    Jonsson, J.E.; Afton, A.D.

    2008-01-01

    Smaller species are less likely to maintain families (or other forms of social groups) than larger species and are more likely to be displaced in competition with larger species. We observed mixed-species flocks of geese in southwest Louisiana and compared frequencies of social groups and success in social encounters of Lesser Snow Geese (Chen caerulescens caerulescens; hereafter Snow Geese) with that of the smaller, closely- related Ross's Geese (C. rossii). Less than 7% of adult and Ross's Geese were in families, whereas 10-22% of adult and 12-15% of juvenile Snow Geese were in families. Snow Geese won 70% of interspecific social encounters and had higher odds of success against Ross's Geese than against individuals of their own species. The larger Snow Geese maintain families longer than Ross's Geese, which probably contributes to their dominance over Ross's Geese during winter. Predator vigilance probably is an important benefit of mixed flocking for both species. We suggest the long-standing association with Snow Geese (along with associated subordinate social status) has selected against family maintenance in Ross's Geese.

  1. Collaborative Research and Education in the Ross Sea: A broader impact evaluation report

    NASA Astrophysics Data System (ADS)

    Parsons, C.; Kohut, J. T.; Lichtenwalner, C. S.; Clark, H.

    2010-12-01

    An interdisciplinary team of researchers will focus on describing the high productivity patchiness observed in phytoplankton blooms in the mid-to-late summer in the Ross Sea, Antarctica. They will use a novel sampling strategy that employs a remotely controlled glider (AUV) to locate and map circumpolar deep water in near real time and also to direct further ship-based sampling. This unusual coordination of a polar research vessel with AUVs provides an exciting opportunity to engage formal and informal educators in a research adventure. As part of this NSF-funded project’s Criterion 2 broader impact, joining the researchers virtually will be 30 New Jersey middle-school teachers and their students. This summer in New Jersey, in partnership with Liberty Science Center educators, COSEE-NOW (Centers for Ocean Sciences Education Excellence-Networked Ocean World) and Woods Hole Oceanographic Institution, the project team introduced teachers to the Ross Sea, the research, the science behind it and the AUV. The summer workshop and ongoing schoolyear support is providing the teachers with the tools they need to bring the excitement of the research into their classrooms in real time during the Ross Sea cruise at the end of this year. This presentation by Chris Parsons, the project evaluator, will summarize the evaluation plan for this broader impact project, which follows teachers and their classes for a year, and provide the latest evaluation results from this project.

  2. Frank Ross's Early Orbits of the First Irregular Satellites of Saturn and Jupiter

    NASA Astrophysics Data System (ADS)

    Osterbrock, Donald E.

    2006-12-01

    Frank E. Ross, later the inventor of the wide-angle lens, photographic photometer, and correcting lens for large reflecting telescopes, developed for the 200-inch, that bear his name, was also an expert on celestial mechanics. After earning his PhD at Berkeley in 1901, he worked in Washington as chief assistant to Simon Newcomb, the leading astronomer of his time, until the latter's death in 1909. W. H. Pickering, who had discovered Phoebe, the first distant, irregular satellite of Saturn, was unable to calculate an orbit for it. He asked Newcomb to do it, but the "grim dean of American astronomy" was too busy, and turned the task over to Ross to do, mostly on his own time. The young assistant succeeded, but spent many sleepless nights on the job. He and his brother Walter were also running a cigar store in Washington at the time. Charles D. Perrine at Lick Observatory discovered J VI and J VII, the first two similar satellites of Jupiter, in 1904 and 1905, and could not obtain satisfactory orbits for them either, even with Director W. W. Campbell's help. Ross then calculated their orbits also, again at a tremendous cost of effort. He used log tables, pencil and paper, and a simple adding machine for his computing tasks, as all "computers" (persons) did at that time. These three satellites were the first to be discovered by photography.

  3. Tidal Modulation of Ice-shelf Flow: a Viscous Model of the Ross Ice Shelf

    NASA Technical Reports Server (NTRS)

    Brunt, Kelly M.; MacAyeal, Douglas R.

    2014-01-01

    Three stations near the calving front of the Ross Ice Shelf, Antarctica, recorded GPS data through a full spring-neap tidal cycle in November 2005. The data revealed a diurnal horizontal motion that varied both along and transverse to the long-term average velocity direction, similar to tidal signals observed in other ice shelves and ice streams. Based on its periodicity, it was hypothesized that the signal represents a flow response of the Ross Ice Shelf to the diurnal tides of the Ross Sea. To assess the influence of the tide on the ice-shelf motion, two hypotheses were developed. The first addressed the direct response of the ice shelf to tidal forcing, such as forces due to sea-surface slopes or forces due to sub-ice-shelf currents. The second involved the indirect response of ice-shelf flow to the tidal signals observed in the ice streams that source the ice shelf. A finite-element model, based on viscous creep flow, was developed to test these hypotheses, but succeeded only in falsifying both hypotheses, i.e. showing that direct tidal effects produce too small a response, and indirect tidal effects produce a response that is not smooth in time. This nullification suggests that a combination of viscous and elastic deformation is required to explain the observations.

  4. Subglacial Lake Whillans, West Antarctica; Solute Dynamics and Fluxes to the Ross Sea

    NASA Astrophysics Data System (ADS)

    Skidmore, M. L.; Michaud, A. B.; Achberger, A.; Barbante, C.; Christner, B. C.; Mikucki, J.; Mitchell, A. C.; Priscu, J. C.; Purcell, A. M.; van Gelder, W.; Vick-Majors, T.

    2014-12-01

    Subglacial Lake Whillans is located beneath the Whillans Ice Stream in West Antarctica. The lake is situated beneath 800 m of ice and ~ 70 km upstream of the grounding line where Whillans Ice Stream terminates into the Ross Sea. Subglacial Lake Whillans is a shallow lake and a component of a complex subglacial hydrological system that may resemble a large wetland along the Siple Coast of West Antarctica. Subglacial Lake Whillans drains and refills on a sub-decadal time scale discharging water towards the Ross Sea. Water and sediment samples were recovered from the lake, using clean access drilling technologies, in January, 2013. Isotopic analysis of the lake waters indicates basal meltwater from the ice sheet as the dominant water source. Geochemical analysis of the lake water reveals it is freshwater with mineral weathering as a significant solute source, with a minor contribution from sea water likely from relict marine sediments. Subglacial hydrothermal activity upstream may also contribute solutes. Nutrients N and P are present at micromolar concentrations. Sediment porewaters from shallow cores (~ 40 cm depth) of the subglacial lake sediments indicate increasing solute concentration with depth, with up to ~ five times greater solute concentrations than in the lake water. The waters and sediment contain metabolically active organisms which are likely involved in elemental cycling within the lake system. Here we will discuss solute sources to the lake, solute dynamics within the lake waters and sediment, and the fluxes of solute and nutrients to the Ross Sea and their implications for these marine ecosystems.

  5. Accumulation and marine forcing of ice dynamics in the western Ross Sea during the last deglaciation

    NASA Astrophysics Data System (ADS)

    Hall, Brenda L.; Denton, George H.; Heath, Stephanie L.; Jackson, Margaret S.; Koffman, Tobias N. B.

    2015-08-01

    The grounding line of the ice sheet in the Ross Sea, Antarctica, retreated between the Last Glacial Maximum and the present. However, the timing of the retreat and the interplay of factors controlling ice stability in this region remain uncertain. Here we use 180 radiocarbon dates to reconstruct the chronology of moraine construction on the headlands adjacent to western McMurdo Sound. On the basis of these dates we then assess the timing of ice expansion and retreat in the Ross drainage system that is fed from both the East and West Antarctic ice sheets. We find that grounded ice in the western Ross Sea achieved its greatest thickness and extent during the last termination, between 12,800 and 18,700 years ago. Maximum ice thickness at our site coincides with a period of high accumulation as recorded by the West Antarctic Ice Sheet Divide ice core. Recession of the ice sheet from the headland moraines began about 12,800 years ago, despite continued high accumulation and the expansion of land-based glaciers at this time. We therefore suggest that the grounding-line retreat reflects an increased marine influence as sea levels rose and the ocean warmed. We suggest that future instability in the ice sheet grounding line may occur whenever the ocean forcing is stronger than forcing from accumulation.

  6. Competing connections between the Ross Ice Shelf with the Southern Ocean.

    NASA Astrophysics Data System (ADS)

    Jendersie, Stefan

    2016-04-01

    The stability of the Ross Ice Shelf (RIS) is critical to both the East Antarctic Ice Sheet, and the West Antarctic Ice Sheet. Results from a climatological ice shelf-ocean coupled numerical model (ROMS) suggest a new circulation mechanism associated with High Salinity Water (HSSW) production in the Ross Sea Polynya (RSP) that controls oceanic heat access to the RIS cavity. Within the RSP the dense water-saturated water column contracts during winter and causes a seasonal drop in Sea Surface Height (SSH) localised to a convection chimney under the RSP. The SSH gradients of up to 1.5 mm per km are sufficient to generate a barotropic pressure gradient that can counteract the wide scale horizontal baroclinic force and reverse the geostrophic circulation. In water depths between 600 and 800 m north of the western RIS the effect causes the seasonal occurrence of a cyclonic circulation cell with transports greater than 1Sv. Appearing with the beginning of winter sea ice formation in the RSP it significantly changes the dynamics at the ice shelf front. The new mechanism is described as one element in a framework of oceanographic processes that mitigate the exchange between the deep ocean and the ocean cavity under the RIS. Our study links local circulation features that are known from observation and previous model studies, and for the first time establishes a coherent system of responsible physical forcing processes in the Ross Sea.​

  7. Forced copulation results in few extrapair fertilizations in Ross's and lesser snow geese

    USGS Publications Warehouse

    Dunn, P.O.; Afton, A.D.; Gloutney, M.L.; Alisauskas, R.T.

    1999-01-01

    Extrapair paternity varies from 0 to over 70% of young among various populations of birds. Comparative studies have suggested that this variation is related to nesting density, breeding synchrony and the proportion of extrapair copulations. We used minisatellite DNA fingerprinting to examine levels of extrapair paternity in Ross's geese, Chen rossi, and lesser snow geese, C. caerulescens c. (hereafter snow geese) nesting in the largest known goose colony in the world. These geese have one of the highest known percentages of extrapair copulation (46-56% of all attempted copulations), and all of these appeared to be forced. Among all successful copulations, 33 and 38% were extrapair in Ross's and snow geese, respectively. Despite the high percentage of extrapair copulations, extrapair paternity was low in both Ross's and snow geese (2-5% of young). Extrapair paternity was not related to nest density in either species. However, in snow geese, extrapair paternity was more likely to occur in nests of females that nested asynchronously, either early or late in the season. This is one of a few reported examples of a negative relationship between extrapair paternity and breeding synchrony. Extrapair young also tended to come from eggs laid later in the clutch. Although forced extrapair copulations appear to be a relatively inefficient reproductive tactic for males, they may provide a reproductive advantage for some males.

  8. Shallow structure and geomorphology, northern San Andreas fault, Bodega Bay to Fort Ross, California

    NASA Astrophysics Data System (ADS)

    Johnson, S. Y.; Hartwell, S. R.; Manson, M. W.

    2013-12-01

    We mapped a 35-km-long section of the northwest-trending San Andreas fault zone (SAFZ), extending through Bodega Bay, crossing the onshore Bodega Head isthmus, and continuing in the offshore to Fort Ross, California. Mapping is based on integrated analysis of high-resolution seismic-reflection profiles (38 fault crossings), multibeam bathymetry and backscatter data, onshore geology, seafloor-sediment samples, and digital camera and video imagery. In Bodega Bay, the SAFZ comprises multiple parallel to subparallel strands that extend through a 2-km-wide basin flanked by massive basement terranes, Cretaceous granitic rock on the southwest and Jurassic and Cretaceous Franciscan Complex on the northeast. Seismic profiles reveal the smooth basin seafloor is underlain by a thin (1 to 12 m) layer of latest Pleistocene and Holocene sediments and an underlying inferred Pleistocene unit characterized by faulted and folded reflections revealing numerous angular unconformities and channels. This geology suggests that Bodega Bay originated as a pull-apart basin formed by an eastern transfer of slip within the SAFZ. If so, the pervasive internal folding and faulting of the young basin fill suggests basin subsidence has largely ended and the basin fill is now being deformed. North of the Bodega Head isthmus, the SAFZ is relatively narrow (200 to 500 m wide) and cuts across relatively flat seafloor covered by sediments derived from the Russian River and Salmon Creek. Gentle fault bends and transfers of slip between subparallel strands have resulted in small fault-zone uplifts and four distinct, elongate (~ 500- to 2300-m long), narrow (~ 200- to 300-m wide) sag basins containing as much as 56 m of inferred latest Pleistocene to Holocene sediment. The offshore mapping suggests the presence of an important, previously unrecognized onshore SAFZ strand cutting across the Bodega Head isthmus about 800 m southwest of the only reported 1906 surface rupture in the map area. Onshore, this

  9. Decadal Changes in Hydrography of the Southern Pacific Ocean and Ross Sea

    NASA Astrophysics Data System (ADS)

    Talley, L. D.; Carter, B.; Warner, M. J.; Swift, J. H.; Orsi, A. H.; Sloyan, B.

    2014-12-01

    Quasi-decadal hydrographic sections of the GO-SHIP program cross the world's oceans with the highest accuracy measurements, documenting temporal variability in physical and chemical properties. The central southern Pacific and Ross Sea have been surveyed regularly along GO-SHIP sections P16S (150W) and S4P (67S) since the first occupation in WOCE in 1992. Observed changes are consistent with anthropogenic forcing. The central Ross Sea gyre's bottom 1000 m is nearly adiabatic (well mixed), and well-ventilated based on chlorofluorocarbon (CFC) and sulfur hexafluoride observations (see Figure), and can be easily compared from one survey to the next. This Ross Sea bottom layer observed in March, 2014, on P16S continued to warm, with a monotonic increase over the 4 WOCE/GO-SHIP surveys thus far: 1992, 2005, 2011, and now 2014 (see Figure). Deep temperature has increased by 0.1°C since 1992, continuing the trend of enhanced global ocean deep warming in the Southern Ocean documented by Purkey/Johnson (2010) and IPCC AR5 WG1. The abyssal central Ross Sea waters also continued to freshen slightly. The upper ocean in the Ross Sea warmed, became more stratified, had higher nutrients and total carbon, and was less ventilated in terms of apparent oxygen utilization than in 2005. North of the Antarctic Circumpolar Current along 150W, the upper ocean's Subantarctic Mode Water became saltier, also continuing the subtropical trend of the past several decades (Durack/Wijffels 2010), with an apparently stronger incursion of saline subtropical waters that render it more salt and temperature stratified, ruling out a local deep mixed layer formation mechanism, with an increasing tendency towards double diffusive processes. The Antarctic Intermediate Water salinity minimum continued to freshen. The arrival in 2014 of CFC's at the ocean bottom between 32S and 40S indicates that the Antarctic Bottom Water there is about 40-50 years old. CFCs in the ocean's surface layer decreased, in

  10. Atmospheric forcing of sea ice anomalies in the Ross Sea Polynya region

    NASA Astrophysics Data System (ADS)

    Dale, Ethan; McDonald, Adrian; Rack, Wolfgang

    2016-04-01

    Despite warming trends in global temperatures, sea ice extent in the southern hemisphere has shown an increasing trend over recent decades. Wind-driven sea ice export from coastal polynyas is an important source of sea ice production. Areas of major polynyas in the Ross Sea, the region with largest increase in sea ice extent, have been suggested to produce the vast amount of the sea ice in the region. We investigate the impacts of strong wind events on polynyas and the subsequent sea ice production. We utilize Bootstrap sea ice concentration (SIC) measurements derived from satellite based, Special Sensor Microwave Imager (SSM/I) brightness temperature images. These are compared with surface wind measurements made by automatic weather stations of the University of Wisconsin-Madison Antarctic Meteorology Program. Our analysis focusses on the winter period defined as 1st April to 1st November in this study. Wind data was used to classify each day into characteristic regimes based on the change of wind speed. For each regime, a composite of SIC anomaly was formed for the Ross Sea region. We found that persistent weak winds near the edge of the Ross Ice Shelf are generally associated with positive SIC anomalies in the Ross Sea polynya area (RSP). Conversely we found negative SIC anomalies in this area during persistent strong winds. By analyzing sea ice motion vectors derived from SSM/I brightness temperatures, we find significant sea ice motion anomalies throughout the Ross Sea during strong wind events. These anomalies persist for several days after the strong wing event. Strong, negative correlations are found between SIC within the RSP and wind speed indicating that strong winds cause significant advection of sea ice in the RSP. This rapid decrease in SIC is followed by a more gradual recovery in SIC. This increase occurs on a time scale greater than the average persistence of strong wind events and the resulting Sea ice motion anomalies, highlighting the production

  11. A case study of a Ross Ice Shelf Airstream event using high resolution observational data captured by SNOWWEB

    NASA Astrophysics Data System (ADS)

    Jolly, Ben; McDonald, Adrian

    2015-04-01

    The Ross Ice Shelf Airstream (RAS) is the dominant weather pattern over the Ross Ice Shelf in Antarctica. Characterised by a strong southerly flow over the ice shelf, the RAS plays a significant role in the northward transport of cold air from the interior of the continent out into the Ross Sea. As it passes by Ross Island - home to McMurdo Station and Scott Base - and out over the edge of the ice shelf, the RAS also helps to create and maintain the Ross Sea Polynya, the single largest contributor to sea ice growth in the Ross Sea region. Our area of interest is the McMurdo Ice Shelf, situated directly south of Ross Island and adjoining the north-western tip of the much larger Ross Ice Shelf. The terrain of this region is complex, with large mountains, islands, and cliffs dominating local flow. Additionally, severe weather - often experienced during a RAS event - can greatly impact human activity. These two factors make this region particularly interesting to study. During the 2013/14 austral summer season we deployed 14 weather stations on the McMurdo Ice Shelf, creating a dense spatial observational network. In combination with existing automatic weather stations and high resolution model output from the Antarctic Mesoscale Prediction System (AMPS), we present a case study of a three day RAS event observed in November 2013. We find that AMPS represents the RAS well in general, however at the local scale there are some large discrepancies between observed and forecast winds. Predominantly these are a result of errors in timing, with AMPS incorrectly forecasting 'lulls' in the RAS when none were observed and vice-versa. There also appear to be some differences between AMPS and observations regarding the split of the southerly RAS flow around Ross Island. The representation within AMPS of both Hut Point Peninsula - a small yet important orographic feature running south-west from Ross Island that blocks relatively weak flows - and the Windless Bight high pressure

  12. X-ray Ross filter method for impurity transport studies on DIII-D (abstract)

    NASA Astrophysics Data System (ADS)

    Bogatu, I. N.; Kim, J. S.; Egdell, D. H.; Snider, R. T.; Brooks, N. H.; Wade, M. R.; West, W. P.

    2001-01-01

    The injection of Ar into the region of the DIII-D divertor is a promising technique for energy dissipation (through radiation and collisions) and consequently for reduction of the heat load on the plates. An important problem related to this technique, is the inherent poisoning of the core plasma by migrating Ar. The Ar core contamination seems also to improve the thermal transport in an advanced operating mode of the tokamak. It is therefore of great importance to measure the evolution of the impurity concentration profile within the core plasma. This goal could be achieved by using the Ross filter method in conjunction with the existing x-ray diagnostics on DIII-D. A basic Ross filter system consists of two identical detectors placed behind two different x-ray absorbing foils looking at the same plasma volume. The foils are made of different elements or compounds with adjacent or nearly adjacent atomic numbers. Their accurate thickness causes the x-ray transmission curves of the two foils to be effectively identical over the entire energy range except within the narrow region between their absorption edges. Since the transmission characteristics of the foils above and below their absorption edges are the same, any difference in the two detected signals is proportional to the total x-ray power of the emission spectrum between these two edge energies. An x-ray Ross filter with its energy pass band centered on the Ar XVII Kα line at 3.14 keV has been designed. This allows for the discrimination of the Ar Kα line only, regardless of Ar ionization state, against any background radiation with energies outside the energy pass band. The Ross filter was installed in front of two of the fan shaped poloidal x-ray arrays on DIII-D. The first measurements showed very good discrimination against Ne, another injected impurity. Emissivity profile evolution of the Kα lines and Ar enhanced continuum within the energy pass band of the Ross filter can be determined from the x

  13. A 45,000 yr record of Adélie penguins and climate change in the Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Emslie, Steven D.; Coats, Larry; Licht, Kathy

    2007-01-01

    Well-preserved remains of bone, tissue, and eggshell of Adélie Penguin (Pygoscelis adeliae) have been recovered from numerous abandoned colonies in the Ross Sea region, Antarctica. Radiocarbon dates on these remains provide an occupation history for this species ranging from hundreds to tens of thousands of years ago. We completed 62 new radiocarbon dates on these remains, which now indicate that an open-water marine environment existed in the Ross Sea from ca. 45,000 to 27,000 14C yr before present (B.P.) and provide constraints for the timing of the last advance of the Ross Ice Sheet. Penguins did not recolonize the Ross Sea until ca. 8000 calendar years (cal yr) B.P., after the early Holocene retreat of the Ross Ice Sheet. Two subsequent periods of abandonment at 5000 4000 and 2000 1100 cal yr B.P. correlate with cooling episodes that caused unfavorable marine conditions for breeding penguins. Most modern colonies were established only within the past 2000 yr.

  14. Glucose fluxes and concentrations of dissolved combined neutral sugars (polysaccharides) in the Ross Sea and Polar Front Zone, Antarctica

    NASA Astrophysics Data System (ADS)

    Kirchman, David L.; Meon, Benedikt; Ducklow, Hugh W.; Carlson, Craig A.; Hansell, Dennis A.; Steward, Grieg F.

    We hypothesized that dissolved carbohydrates would be large components of the labile dissolved organic carbon (DOC) pool and would support much bacterial growth in Antarctic waters, especially the Ross Sea, since previous work had observed extensive phytoplankton blooms with potentially high production rates of carbohydrates in Antarctic seas. These hypotheses were tested on cruises in the Ross Sea and Antarctic Polar Front Zone as part of the US JGOFS program. Concentrations and fluxes of free glucose (the only free sugar detected) were very low, but dissolved polysaccharides appeared to be important components of the DOC pool. Concentrations of dissolved combined neutral sugars increased >3-fold during the phytoplankton bloom in the Ross Sea and were a large fraction (ca. 50%) of the semi-labile fraction of DOC. The relatively high concentrations of dissolved combined neutral sugars, which are thought to be quite labile, appear to explain why DOC accumulated during the phytoplankton bloom was degraded so quickly once the bloom ended. Some of the polysaccharides appeared to be more refractory, however, since dissolved combined neutral sugars were observed in deep waters (>550 m) and in early spring (October) in the Ross Sea, apparently having survived degradation for >8 months. The molecular composition of these refractory polysaccharides differed from that of polysaccharides sampled during the phytoplankton bloom. Fluxes of DOC were low in the Ross Sea compared to standing stocks and fluxes of particulate material, but the DOC that did accumulate during the phytoplankton bloom appeared to be sugar-rich and relatively labile.

  15. Ross operation in children and young adults: the Alder Hey case series

    PubMed Central

    Raja, Shahzad Gull; Pozzi, Marco

    2004-01-01

    Background The ideal prosthesis for aortic valve replacement in children and young adults has not been found yet. In recent years there has been a renewed interest in the replacement of aortic valve with the pulmonary autograft owing to its advantages of lack of anticoagulation, potential for growth and excellent haemodynamic performance. The purpose of this study was to review our institutional experience at Alder Hey hospital with the Ross procedure in children and young adults. Methods From November 1996 to September 2003, 38 patients (mean age, 13.1 ± 5.7 years) underwent the Ross procedure for various aortic valve diseases using the root replacement technique. Clinical and echocardiographic follow-up was performed early (within 30 days), 3 to 6 months, and yearly after surgery. Medical records of all patients were reviewed retrospectively. Results There was 1 perioperative death. The patients were followed-up for a median interval of 36 months and up to 7 years. One patient died 3 years after surgery secondary to ventricular arrhythmia with overall mortality of 5.3%. Actuarial survival at 7 years was 94 ± 2.5% and there was 100% freedom from reoperation for autograft valve dysfunction or any other cause. Balloon dilatation was required in 2 patients for pulmonary homograft stenosis. The haemodynamics at the latest follow-up were also similar to those at the time of discharge after surgery. There was no progression in the degree of aortic regurgitation for 11 patients with trivial and 3 with mild regurgitation. Conclusion Our experience demonstrates that Ross operation is an attractive option for aortic valve replacement in children and young adults. Not only can the operation be accomplished with a low operative risk but the valve function stays normal over a long period of time with minimal alteration in lifestyle and no need for repeated operations to replace the valve as a result of somatic growth of the children. PMID:15096281

  16. Deep structure in rifted crust at the ocean-continent margin in the northwestern Ross Sea

    NASA Astrophysics Data System (ADS)

    Selvans, M. M.; Clayton, R. W.; Stock, J. M.; Cande, S. C.; Davey, F. J.

    2010-12-01

    The Ross Sea contains several deep sedimentary basins which formed as a result of distributed extension in continental crust during Cenozoic and Cretaceous time. These basins contain sedimentary sequences that are laterally extensive across multiple basins, which in the western Ross Sea represent infill from erosion of the Transantarctic Mountains. The Northern Basin lies in the northwestern Ross Sea, and borders oceanic crust that includes the Adare Trough spreading center, active from 43 to 26 Ma. This area provides an ideal location to study the mechanisms by which strain localized in a spreading center is transferred to adjacent continental crust. Refraction seismic records from 74 sonobuoys with 20 to 30 km of offset were obtained in the Northern and Adare Basins during research cruise NBP0701; they complement the ~2,700 km of multi-channel seismic (MCS) data, by probing the deeper velocity structure of the crust and by providing direct detection of layer velocities. We use standard techniques including linear moveout and conversion of the data into τ-p space (intercept time and slowness) to determine layer depths and velocities; we also construct a finite difference model of each sonobuoy in order to recognize converted phases, confidently tie the refracted arrivals to the reflections from which they originate (which are then tied to the shallower MCS data), and constrain layers’ s-wave velocities. In further support of the hypothesis that volcanic intrusions contributed significantly to the process of extension in the Northern Basin, high crustal velocities do not appreciably deepen when moving from the Adare Basin into the Northern Basin, as would be expected when moving from oceanic to continental crust. We consistently detect high crustal velocities at only a few kilometers depth into the crust, implying that processes such as compaction and erosion of sediment layers and volcanic intrusion have a significant effect on crustal structure.

  17. Seismic observations of sea swell on the floating Ross Ice Shelf, Antarctica

    NASA Astrophysics Data System (ADS)

    Cathles, L. M.; Okal, Emile A.; Macayeal, Douglas R.

    2009-06-01

    A seismometer operating on the floating Ross Ice Shelf near its seaward ice front (Nascent Iceberg) for 340 days (out of 730 days) during the 2004, 2005, and 2006 Antarctic field seasons recorded the arrival of 93 distantly sourced ocean swell events displaying frequency dispersion characteristic of surface gravity waves propagating on deep water. Comparison of swell event dispersion with the NOAA Wave Watch III (NWW3) ocean wave model analysis reveals that 83 of these events were linked to specific storms located in the Pacific, Southern, and Indian oceans. Nearly all major storms in the NWW3 analysis of the Pacific Ocean were linked to signals observed at the Nascent site during the period of seismometer operation. Swell-induced motion of the Ross Ice Shelf is found to increase by several orders of magnitude over the time period that sea ice surrounding Antarctica decreases from its maximum extent (October) to its minimum extent (February). The amplitude of vertical vibration of the ice shelf in the frequency band between 0.025 and 0.14 Hz varies between tens of micrometers to millimeters as sea ice decays to its minimum seasonal extent. This suggests that climate influence on sea ice extent may indirectly modulate swell energy incident on the calving margins of the Antarctic Ice Sheet. The largest swell signals observed on the Ross Ice Shelf come from storms in the tropical Pacific and Gulf of Alaska. These remote events emphasize how the iceberg calving margin of Antarctica is connected to environmental conditions well beyond Antarctica.

  18. Marine record of Holocene climate, ocean, and cryosphere interactions: Herbert Sound, James Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Minzoni, Rebecca Totten; Anderson, John B.; Fernandez, Rodrigo; Wellner, Julia Smith

    2015-12-01

    The sediment record offshore James Ross Island, northeast Antarctic Peninsula presents an unparalleled opportunity to directly compare marine and terrestrial climate records spanning the Holocene in maritime Antarctica. An 11 m drill core was collected between Herbert Sound and Croft Bay as part of the SHALDRIL NBP-0502 initiative and produced the southernmost sediment record from the eastern side of the AP. Thirty-eight radiocarbon ages are used to construct an age model of centennial-scale resolution. Multi-proxy records, including magnetic susceptibility, pebble content, particle size, total organic carbon, and diatom assemblages, were interrogated in the context of nearby Holocene-age ice core, lake, and drift records from James Ross Island. Differences in the timing and expression of Holocene events reflect marine controls on tidewater glaciers, such as water mass configurations and sea ice. Glacial behavior mimics ice core paleotemperatures during the Holocene, with the exception of distinct ocean warming events. Herbert Sound was fully occupied by grounded ice during the Last Glacial Maximum, and experienced rapid lift-off, followed by a floating ice phase. The canopy of floating ice receded by 10 ± 2.4 cal kyr BP, presumably in response to Early Holocene warming. Herbert Sound and Croft Bay fully deglaciated by 7.2 cal kyr BP, when the Mid Holocene Hypsithermal commenced and the sound became open and productive. An extreme peak in productivity ˜6.1 cal kyr BP indicates an oceanic warming event that is not reflected in atmospheric temperature or lacustrine sediment records. Increase in sea ice cover and ice rafting mark the onset of the Neoglacial ˜2.5 cal kyr BP, when pronounced atmospheric cooling is documented in the James Ross Island ice core. Our comparison facilitates more holistic understanding of atmosphere-ocean-cryosphere interactions that may aid predictions of glacial response to future warming and sea-level scenarios.

  19. Chili Cookoff: Unique Ingredients Prove Successful in Ross Smith’s Big Pot of Chili | Poster

    Cancer.gov

    By Ashley DeVine, Staff Writer If the past is any indication, judges at the Protective Services Chili Cookoff give high marks for chili recipes containing unique or uncommon ingredients. Previous winning recipes have included ingredients such as black beans, pumpkin, pineapple, pork loin, and even bourbon. Judges at the 12th annual event, held Jan. 5, continued this tradition by voting for Ross Smith’s Big Pot of Chili, which featured three types of meat, four different sauces, baker’s chocolate, and parmesan rind.  

  20. The relevance of buttressing for Filchner-Ronne and Ross Ice Shelf

    NASA Astrophysics Data System (ADS)

    Reese, Ronja; Gudmundsson, Hilmar; Levermann, Anders; Winkelmann, Ricarda

    2016-04-01

    Sub-shelf melting is an important component of Antarctica's mass budget. Although thinning of ice shelves does not directly contribute to sea-level rise, it may have a significant indirect impact through the potential of ice shelves to buttress their adjacent ice sheet. This is clearly seen in recent observations, e.g. in the Amundsen region (Pritchard et al., 2012) or at the Southern Antarctic Peninsula (Wouters et al, 2015) where increased ice loss of the adjacent upstream drainage basins is attributed to enhanced sub-shelf melting. In the extreme case, the complete disintegration of an ice shelf, e.g. during the calving events of Larsen A and B in 1995 and 2002, respectively, the adjacent ice streams subsequently accelerated significantly (Scambos et al., 2014). Here, we investigate the importance of buttressing using the finite-element, shallow-stream approximation numerical model Úa. We derive transfer functions for an idealized setup (Gudmundsson et al. 2012) and the Filchner-Ronne and Ross Ice Shelf. They allow for the computation of instantaneous changes in velocities to thickness perturbation patterns. Based on the transfer functions, we calculate the sensitivity of flux across the grounding line to regional varying melting patterns for the idealized setup and for Filchner-Ronne and Ross Ice Shelf. We find that the immediate response of velocities in the ice shelf-ice sheet system to changes in sub-shelf melting can be understood as the interaction of two effects: On the one hand, the spreading rate is a function of local ice thickness, indicating that a thinning of the ice shelf reduces velocities. On the other hand, ice shelf thinning weakens its ability to buttress, and thus enhances velocities. These two processes compete, leading to a complex pattern of velocity changes within the ice shelf. We find - both in the idealized setup and for Ross and Filchner-Ronne Ice Shelves - that the reduction in buttressing is dominating the velocity changes in the

  1. STS-110 M.S. Smith and Ross in slidewire basket during TCDT

    NASA Technical Reports Server (NTRS)

    2002-01-01

    KENNEDY SPACE CENTER, FLA. -- STS-110 Mission Specialists Steven L. Smith (left) and Jerry L. Ross (right) get ready to climb out of the slidewire basket, part of emergency egress equipment on the launch pad.. The crew is taking part in Terminal Countdown Demonstration Test activities, which also include a simulated launch countdown, held at KSC prior to each Space Shuttle flight. Scheduled for launch April 4, the 11-day mission will feature Shuttle Atlantis docking with the International Space Station (ISS) and delivering the S0 truss, the centerpiece-segment of the primary truss structure that will eventually extend over 300 feet.

  2. STS-110 M.S. Smith, Ross, and Walheim in Atlantis during TCDT

    NASA Technical Reports Server (NTRS)

    2002-01-01

    KENNEDY SPACE CENTER, FLA. -- (Left to right) STS-110 Mission Specialists Steven Smith, Jerry Ross and Rex Walheim settle into their seats aboard Space Shuttle Atlantis prior to a simulated launch countdown. The simulation is part of Terminal Countdown Demonstration Test activities. TCDT also includes emergency egress training and is held at KSC prior to each Space Shuttle flight. Scheduled for launch April 4, the 11-day mission will feature Shuttle Atlantis docking with the International Space Station (ISS) and delivering the S0 truss, the centerpiece-segment of the primary truss structure that will eventually extend over 300 feet.

  3. STS-110 M.S. Ross and Smith in M-113 personnel carrier during TCDT

    NASA Technical Reports Server (NTRS)

    2002-01-01

    KENNEDY SPACE CENTER, FLA. -- With STS-110 Mission Specialists Jerry Ross (far left) and Steven Smith (third from left) on board, Commander Michael Bloomfield scatters dust as he practices driving the M-113 armored personnel carrier. The driving is part of Terminal Countdown Demonstration Test activities, which include emergency egress training and a simulated launch countdown. The TCDT is held at KSC prior to each Space Shuttle flight. Scheduled for launch April 4, the 11-day mission will feature Shuttle Atlantis docking with the International Space Station (ISS) and delivering the S0 truss, the centerpiece-segment of the primary truss structure that will eventually extend over 300 feet.

  4. Remote sensing study of land use and sedimentation in the Ross Barnett Reservoir, Jackson, Mississippi area

    NASA Technical Reports Server (NTRS)

    Mealor, W. T., Jr.; Pinson, T. W.; Wertz, D. L.; Hoskin, C. M.; Williams, D. C.

    1972-01-01

    This multi-year study is aimed at focusing on the recognition of sediment and other affluents in a selected area of the Ross Barnett Reservoir. The principle objectives are the determination of land use types, effect of land use on erosion, and the correlation of sediment with land use in the area. The I2S multi-band imagery was employed in conjunction with ground truth data for both water and land use studies. The selected test site contains approximately forty square miles including forest, open land, and water in addition to residential and recreational areas.

  5. Core drilling through the ross ice shelf (antarctica) confirmed Basal freezing.

    PubMed

    Zotikov, I A; Zagorodnov, V S; Raikovsky, J V

    1980-03-28

    New techniques that have been used to obtain a continuous ice core through the whole 416-meter thickness of the Ross Ice Shelf at Camp J-9 have demonstrated that the bottom 6 meters of the ice shelf consists of sea ice. The rate of basal freezing that is forming this ice is estimated by different methods to be 2 centimeters of ice per year. The sea ice is composed of large vertical crystals, which form the waffle-like lower boundary of the shelf. A distinct alignment of the crystals throughout the sea ice layer suggests the presence of persistent long-term currents beneath the ice shelf. PMID:17779616

  6. Maceral, total organic carbon, and palynological analyses of ross ice shelf project site j9 cores.

    PubMed

    Wrenn, J H; Beckman, S W

    1982-04-01

    Analyses of macerals and total organic carbon indicate that the low organic content of core sediments from Ross Ice Shelf Project site J9 has been selectively reduced further, probably by postdepositional submarine oxidation. Palynological analysis revealed a reworked Paleogene dinocyst flora of low diversity (the transantarctic flora). This constitutes the most southerly dinocyst flora reported thus far. The antarctic distribution of the transantarctic flora supports the existence of a transantarctic strait during the Paleogene. The J9 sporomorph assemblage also is reworked and Paleogene in age. PMID:17736253

  7. Mixed-phase cloud radiative properties over Ross Island, Antarctica: The influence of various synoptic-scale atmospheric circulation regimes

    NASA Astrophysics Data System (ADS)

    Scott, Ryan C.; Lubin, Dan

    2014-06-01

    Spectral downwelling shortwave irradiance measurements made beneath overcast stratiform cloud decks at Ross Island, Antarctica (77.5°S, 167°E), are used in conjunction with discrete ordinates-based radiative transfer simulations to examine how mixed-phase clouds influence shortwave irradiance at the surface during austral spring-summer. From 10 October 2012 until 4 February 2013, an Analytical Spectral Devices (ASD, Inc.) spectroradiometer deployed at the Arrival Heights (77.82°S, 166.65°E) laboratory of McMurdo Station measured in 1 min averages the downwelling spectral hemispheric (direct plus diffuse) irradiance spanning visible (VIS) and near-infrared regions of the solar spectrum, from 350 to 2200 nm. Conservative-scattering cloud optical depth τc is retrieved in the interval 1022-1033 nm, where the albedo of the snow-covered surface is lower than at VIS wavelengths. The impact of liquid versus mixed-phase cloud properties on the surface shortwave energy budget is discerned using irradiances in the 1.6 μm window. Five case studies employ NASA A-Train satellite and ancillary meteorological data sets to investigate the macrophysical, microphysical, and shortwave radiative characteristics of clouds possessing distinct meteorological histories. Cloud systems within marine air masses arriving at Ross Island after transiting the West Antarctic ice sheet (WAIS) and the Ross Ice Shelf are radiatively dominated by the ice phase. In contrast, moist marine air moving directly onshore from the Ross Sea brings low clouds with a stronger influence of liquid water. Deep cyclonic disturbances over the Ross Sea are seen to be limited in their ability to deliver significant moisture as far south as Ross Island, where clouds are mainly optically thin.

  8. Ross ice shelf cavity circulation, residence time, and melting: Results from a model of oceanic chlorofluorocarbons

    NASA Astrophysics Data System (ADS)

    Reddy, Tasha E.; Holland, David M.; Arrigo, Kevin R.

    2010-04-01

    Despite their harmful effects in the upper atmosphere, anthropogenic chlorofluorocarbons dissolved in seawater are extremely useful for studying ocean circulation and ventilation, particularly in remote locations. Because they behave as a passive tracer in seawater, and their atmospheric concentrations are well-mixed, well-known, and have changed over time, they are ideal for gaining insight into the oceanographic characteristics of the isolated cavities found under Antarctic ice shelves, where direct observations are difficult to obtain. Here we present results from a modeling study of air-sea chlorofluorocarbon exchange and ocean circulation in the Ross Sea, Antarctica. We compare our model estimates of oceanic CFC-12 concentrations along an ice shelf edge transect to field data collected during three cruises spanning 16 yr. Our model produces chlorofluorocarbon concentrations that are quite similar to those measured in the field, both in magnitude and distribution, showing high values near the surface, decreasing with depth, and increasing over time. After validating modeled circulation and air-sea gas exchange through comparison of modeled temperature, salinity, and chlorofluorocarbons with field data, we estimate that the residence time of water in the Ross Ice Shelf cavity is approximately 2.2 yr and that basal melt rates for the ice shelf average 10 cm yr -1. The model predicts a seasonal signature to basal melting, with highest melt rates in the spring and also the fall.

  9. Astronaut Ross Approaches Assembly Concept for Construction of Erectable Space Structure (ACCESS)

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The crew assigned to the STS-61B mission included Bryan D. O'Conner, pilot; Brewster H. Shaw, commander; Charles D. Walker, payload specialist; mission specialists Jerry L. Ross, Mary L. Cleave, and Sherwood C. Spring; and Rodolpho Neri Vela, payload specialist. Launched aboard the Space Shuttle Atlantis November 28, 1985 at 7:29:00 pm (EST), the STS-61B mission's primary payload included three communications satellites: MORELOS-B (Mexico); AUSSAT-2 (Australia); and SATCOM KU-2 (RCA Americom). Two experiments were conducted to test assembling erectable structures in space: EASE (Experimental Assembly of Structures in Extravehicular Activity), and ACCESS (Assembly Concept for Construction of Erectable Space Structure). In a joint venture between NASA/Langley Research Center in Hampton, Virginia, and the Marshall Space Flight Center (MSFC), EASE and ACCESS were developed and demonstrated at MSFC's Neutral Buoyancy Simulator (NBS). In this STS-61B onboard photo, astronaut Ross, perched on the Manipulator Foot Restraint (MFR) approaches the erected ACCESS. The primary objective of these experiments was to test the structural assembly concepts for suitability as the framework for larger space structures and to identify ways to improve the productivity of space construction.

  10. Ross Works on the Assembly Concept for Construction of Erectable Space Structure (ACCESS) During

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The crew assigned to the STS-61B mission included Bryan D. O'Conner, pilot; Brewster H. Shaw, commander; Charles D. Walker, payload specialist; mission specialists Jerry L. Ross, Mary L. Cleave, and Sherwood C. Spring; and Rodolpho Neri Vela, payload specialist. Launched aboard the Space Shuttle Atlantis November 28, 1985 at 7:29:00 pm (EST), the STS-61B mission's primary payload included three communications satellites: MORELOS-B (Mexico); AUSSAT-2 (Australia); and SATCOM KU-2 (RCA Americom). Two experiments were conducted to test assembling erectable structures in space: EASE (Experimental Assembly of Structures in Extravehicular Activity), and ACCESS (Assembly Concept for Construction of Erectable Space Structure). In a joint venture between NASA/Langley Research Center in Hampton, Virginia, and the Marshall Space Flight Center (MSFC), EASE and ACCESS were developed and demonstrated at MSFC's Neutral Buoyancy Simulator (NBS). In this STS-61B onboard photo, astronaut Ross works on ACCESS high above the orbiter. The primary objective of these experiments was to test the structural assembly concepts for suitability as the framework for larger space structures and to identify ways to improve the productivity of space construction.

  11. STS-61B Astronaut Ross Works on Assembly Concept for Construction of Erectable Space Structure

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The crew assigned to the STS-61B mission included Bryan D. O'Conner, pilot; Brewster H. Shaw, commander; Charles D. Walker, payload specialist; mission specialists Jerry L. Ross, Mary L. Cleave, and Sherwood C. Spring; and Rodolpho Neri Vela, payload specialist. Launched aboard the Space Shuttle Atlantis November 28, 1985 at 7:29:00 pm (EST), the STS-61B mission's primary payload included three communications satellites: MORELOS-B (Mexico); AUSSAT-2 (Australia); and SATCOM KU-2 (RCA Americom). Two experiments were conducted to test assembling erectable structures in space: EASE (Experimental Assembly of Structures in Extravehicular Activity), and ACCESS (Assembly Concept for Construction of Erectable Space Structure). In a joint venture between NASA/Langley Research Center in Hampton, Virginia and the Marshall Space Flight Center (MSFC), EASE and ACCESS were developed and demonstrated at MSFC's Neutral Buoyancy Simulator (NBS). In this STS-61B onboard photo astronaut Ross, located on the Manipulator Foot Restraint (MFR) over the cargo bay, erects ACCESS. The primary objective of this experiment was to test the structural assembly concepts for suitability as the framework for larger space structures and to identify ways to improve the productivity of space construction.

  12. STS-61B Astronauts Ross and Spring Work on Experimental Assembly of Structures in Extravehicular

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The crew assigned to the STS-61B mission included Bryan D. O'Conner, pilot; Brewster H. Shaw, commander; Charles D. Walker, payload specialist; mission specialists Jerry L. Ross, Mary L. Cleave, and Sherwood C. Spring; and Rodolpho Neri Vela, payload specialist. Launched aboard the Space Shuttle Atlantis November 28, 1985 at 7:29:00 pm (EST), the STS-61B mission's primary payload included three communications satellites: MORELOS-B (Mexico); AUSSAT-2 (Australia); and SATCOM KU-2 (RCA Americom). Two experiments were conducted to test assembling erectable structures in space: EASE (Experimental Assembly of Structures in Extravehicular Activity), and ACCESS (Assembly Concept for Construction of Erectable Space Structure). In a joint venture between NASA/Langley Research Center in Hampton, Virginia, and the Marshall Space Flight Center (MSFC), EASE and ACCESS were developed and demonstrated at MSFC's Neutral Buoyancy Simulator (NBS). This STS-61B onboard photo depicts astronauts Ross and Spring working on EASE. The primary objective of these experiments was to test the structural assembly concepts for suitability as the framework for larger space structures and to identify ways to improve the productivity of space construction.

  13. Nursing the dying: implications of Kübler-Ross' staging theory.

    PubMed

    Germain, C P

    1980-01-01

    Society's failure to value the work of nurses, the professionals most frequently involved in the care of the dying, is attributed to a cultural definition of nursing as a second-class occupation and the public's need to deny the realities of the suffering and indignities often associated with the process of dying. Efforts within the field of nursing to improve the care of the dying, by shifting emphasis from a narrow physical focus to a more holistic patient and family focus, preceded the past decade's contributions of Elisabeth Kübler-Ross. Although her staging theory has been cited as having limitations in development and in interpretation, Kübler-Ross' influence towards increasing awareness of the needs of the dying and others experiencing major losses has been substantial as evidenced by many references to staging theory in nursing literature, by a marked increase in attention to holistic care of the dying in the basic and continuing education programs of nursing, and by specialty role development in nursing care of the dying. This decade has also witnessed the major growth of professionalism in nursing, including strides towards professional autonomy. Conflict with the traditional pattern of medical dominance and bureacratic constraints in institutions is inevitable, especially when the medical goal of cure is not attainable. Change to an interdisciplinary model of care is viewed as essential for optimal care of the dying and their families. PMID:10245667

  14. Ross Sea Mollusca from the Latitudinal Gradient Program: R/V Italica 2004 Rauschert dredge samples

    PubMed Central

    Ghiglione, Claudio; Alvaro, Maria Chiara; Griffiths, Huw J.; Linse, Katrin; Schiaparelli, Stefano

    2013-01-01

    Abstract Information regarding the molluscs in this dataset is based on the Rauschert dredge samples collected during the Latitudinal Gradient Program (LGP) on board the R/V “Italica” in the Ross Sea (Antarctica) in the austral summer 2004. A total of 18 epibenthic dredge deployments/samplings have been performed at four different locations at depths ranging from 84 to 515m by using a Rauschert dredge with a mesh size of 500μm. In total 8,359 specimens have been collected belonging to a total of 161 species. Considering this dataset in terms of occurrences, it corresponds to 505 discrete distributional records (incidence data). Of these, in order of abundance, 5,965 specimens were Gastropoda (accounting for 113 species), 1,323 were Bivalvia (accounting for 36 species), 949 were Aplacophora (accounting for 7 species), 74 specimens were Scaphopoda (3 species), 38 were Monoplacophora (1 species) and, finally, 10 specimens were Polyplacophora (1 species). This data set represents the first large-scale survey of benthic micro-molluscs for the area and provides important information about the distribution of several species, which have been seldom or never recorded before in the Ross Sea. All vouchers are permanently stored at the Italian National Antarctic Museum (MNA), Section of Genoa, enabling future comparison and crosschecking. This material is also currently under study, from a molecular point of view, by the barcoding project “BAMBi” (PNRA 2010/A1.10). PMID:24146597

  15. Skeletal and isotopic composition and paleoclimatic significance of late Pleistocene carbonates, Ross Sea, Antarctica

    SciTech Connect

    Taviani, M. ); Reid, D.E.; Anderson, J.B. )

    1993-01-01

    Carbonates cover an extensive area of the northwestern Ross Sea continental shelf. Radiocarbon dates yield late Pleistocene (stage 3) ages for these deposits, hence the carbonates appear to be correlative with widespread tills and glacial marine deposits in the region. Four carbonate facies are recognized on the basis of skeletal composition: a barnacle/foraminifer facies, a muddy bryozoan facies, a bryozoan/barnacle/pelecypod/foraminifer facies, and a planktonic foraminiferal facies. These deposits occur on the shelf and upper slope, while carbonate turbidities derived from them occur on the adjacent continental slope and rise. Compositional analyses of Ross Sea carbonates lend support to previously recognized criteria for identifying cold water carbonates. These include: (1) the presence of an associated ice-rafted component (including dropstones); (2) a dominance of calcite relative to other carbonate minerals (the remaining fraction consists solely of aragonite); (3) allochems that are entirely skeletal; and (4) heavy oxygen isotopic compositions (in the range of +3.0 to +5.1% PDB).

  16. Inland diatoms from the McMurdo Dry Valleys and James Ross Island, Antarctica

    USGS Publications Warehouse

    Esposito, R.M.M.; Spaulding, S.A.; McKnight, Diane M.; Van De Vijver, B.; Kopalova, K.; Lubinski, D.; Hall, B.; Whittaker, T.

    2008-01-01

    Diatom taxa present in the inland streams and lakes of the McMurdo Dry Valleys and James Ross Island, Antarctica, are presented in this paper. A total of nine taxa are illustrated, with descriptions of four new species (Luticola austroatlantica sp. nov., Luticola dolia sp. nov., Luticola laeta sp. nov., Muelleria supra sp. nov.). In the perennially ice-covered lakes of the McMurdo Dry Valleys, diatoms are confined to benthic mats within the photic zone. In streams, diatoms are attached to benthic surfaces and within the microbial mat matrix. One species, L. austroatlantica, is found on James Ross Island, of the southern Atlantic archipelago, and the McMurdo Dry Valleys. The McMurdo Dry Valley populations are at the lower range of the size spectrum for the species. Streams flow for 6-10 weeks during the austral summer, when temperatures and solar radiation allow glacial ice to melt. The diatom flora of the region is characterized by species assemblages favored under harsh conditions, with naviculoid taxa as the dominant group and several major diatom groups conspicuously absent. ?? 2008 NRC.

  17. Glider observations of the biological response to Modified Circumpolar Deep Water Variability in the Ross Sea

    NASA Astrophysics Data System (ADS)

    O'Connell, D.; Kaufman, D.; Friedrichs, M. A.; Smith, W.

    2011-12-01

    The Ross Sea is the most productive area within the Southern Ocean, and is believed to play a significant role in the global marine carbon cycle. This region is also characterized by strong spatial and temporal variability in both physical and biogeochemical conditions; however this variability occurs on spatial and temporal scales that are difficult to resolve with traditional data sources. In order to better understand this variability, two gliders were deployed in the Ross Sea in late November 2010 during the early stages of the summer plankton bloom. Together, the two gliders made over 1500 dives and collected data (salinity, temperature, fluorescence and oxygen) throughout the water column for roughly two months. The data from these gliders were used to identify the presence of the relatively high-nutrient Modified Circumpolar Deep Water (MCDW), which has been hypothesized to be a significant factor affecting the spatial and temporal extent of the summer plankton blooms. Preliminary data analyses indicate a positive correlation between areas of MCDW and high chlorophyll concentrations. The glider data were also compared to contemporaneous cruise data and satellite data and were found to fit well with these other data, yet were better able to resolve the high temporal and spatial variability of this region. Specifically, the lower resolution of the cruise data, as compared to the glider data, made it difficult to resolve the correlation of MCDW to high chlorophyll from the cruise data alone.

  18. Acoustic monitoring in the Ross Sea, Antarctica, using hydrophone of the Ocean Bottom Seismometer

    NASA Astrophysics Data System (ADS)

    Yun, Sukyoung; Lee, Won Sang; Kuk Hong, Jong; Yoo, Hyun Jae; Park, Yongcheol; Schmidt-Aursch, Mechita; Geissler, Wolfram H.

    2016-04-01

    Although a number of active source seismic experiments have been conducted over the last few decades to investigate the crustal structure in the Ross Sea, Antarctica, long-term observation to monitor underwater tectonic activities and changes in the cryospheric environment still remains challenging due to existence of sea ice in the study region. Korea Polar Research Institute has accomplished successful deployment of ocean bottom seismometers (OBS) in the Ross Sea collaborating with Alfred Wegener Institute during the period of 2011-2012 and 2014 by Korean icebreaker RV Araon. The OBS system manufactured by K.U.M. contains a hydrophone sensor that allow us to monitor underwater acoustics generated by tectonic and ice-related events. We present spectrograms of the continuous hydroacoustic data and various types of signals, e.g. seismic T-waves, iceequakes, and tremors. There are periodic and harmonic tremors that might be related with tidal modulation, and the seasonal variation of the background noise seems to be related with sea ice concentration.

  19. Air quality modelling in a stable polar environment—Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Godfrey, J. J.; Clarkson, T. S.

    The CALMET meteorological model and its puff dispersion model CALPUFF have been used in a complex orographic and very stable polar environment to confirm observed plume trajectories under worst case conditions from Scott Base, Ross Island, Antarctica. CALMET has been used to predict the meteorological fields of two characteristic low dispersion days and CALPUFF to predict the pollutant footprint and trajectory for each event. Field work in 1994 used constant density balloon flights to follow the trajectories of air parcels. A commonly occurring light wind condition develops when the prevailing southerly flow is locally deflected by the mountains of Ross Island. This deflection in the wind field produces a light northeasterly flow over Scott Base, which together with a light southeast flow can be associated with the low dispersion of effluent material. The relationship between the synoptic scale southerly flow and the local northeasterly at Scott Base is clearly shown by the diagnostic model and the plume derived by CALPUFF for the Scott Base emissions. The model output is shown to be realistic by the trajectories of constant density balloons.

  20. Recent changes in the flow of the Ross Ice Shelf, West Antarctica

    NASA Astrophysics Data System (ADS)

    Hulbe, Christina L.; Scambos, Ted A.; Lee, Choon-Ki; Bohlander, Jennifer; Haran, Terry

    2013-08-01

    Comparison of surface velocities measured during the Ross Ice Shelf Geophysical and Glaciological Survey (RIGGS, 1973 to 1978) and velocities measured via feature tracking between two Moderate-resolution Imaging Spectroradiometer (MODIS) mosaics (compiled from 2003/4 and 2008/9 images) reveals widespread slowing and minor areas of acceleration in the Ross Ice Shelf (RIS) over the approximately 30 year interval. The largest changes (-13 ma) occur near the Whillans and Mercer Ice Streams grounding line in the southernmost part of the ice shelf. Speed has increased over the interval (up to 5 ma) between the MacAyeal Ice Stream grounding line and the shelf front, and along the eastern shelf front. Changes in ice thickness computed using ICESat laser altimetry are used together with a well-tested model of the ice shelf to investigate underlying causes of change in the flow of the ice shelf over time. The observed transients represent a combination of recent forcings and ongoing response to ice stream discharge variations over the past millennium. While evidence of older events may be present, the modern signal is dominated by shorter time scale events, including the stagnation of Kamb Ice Stream about 160 years ago, recent changes in basal drag on the Whillans Ice Stream ice plain and, perhaps, iceberg calving. Details in embayment geometry, for example the shallow sea floor below Crary Ice Rise, modulate the spatial pattern of ice shelf response to boundary condition perturbations.

  1. Changes on the ice plain of Ice Stream B and Ross Ice Shelf

    NASA Technical Reports Server (NTRS)

    Shabtaie, Sion

    1993-01-01

    During the 1970's and 1980's, nearly 200 stations from which accurate, three dimensional position fixes have been obtained from TRANSIT satellites were occupied throughout the Ross Ice Shelf. We have transformed the elevations obtained by satellite altimetry to the same geodetic datum, and then applied a second transformation to reduce the geodetic heights to elevations above mean sea level using the GEM-10C geoidal height. On the IGY Ross Ice Shelf traverse between Oct. 1957 and Feb. 1958, an accurate method of barometric altimetry was used on a loop around the ice shelf that was directly tied to the sea at both ends of the travel route, thus providing absolute elevations. Comparisons of the two sets of data at 32 station pairs on floating ice show a mean difference of 0 +/- 1 m. The elevation data were also compared with theoretical values of elevations for a hydrostatically floating ice shelf. The mean difference between theoretical and measured values of elevations is -2 +/- 1 m.

  2. STS-55 MS1/PLC Ross and Payload Specialist Walter work in SL-D2 module

    NASA Technical Reports Server (NTRS)

    1993-01-01

    STS-55 Mission Specialist 1 (MS1) and Payload Commander (PLC) Jerry L. Ross floats near cycle ergometer and Rack 9 Anthrorack (AR) (Human Physiology Laboratory) as German Payload Specialist 1 Ulrich Walter reviews a checklist in front of Rack 11 Experiment Rack. These experiment stations and the crewmembers are in the shirt-sleeve environment of the Spacelab Deutsche 2 (SL-D2) science module onboard the Earth-orbiting Columbia, Orbiter Vehicle (OV) 102. In the background is the SL-D2 aft end cone. Behind Ross and Walter is Rack 12 Experiment Rack with Baroreflex (BA).

  3. A coupled ocean-ecosystem model of the Ross Sea: 2. Iron regulation of phytoplankton taxonomic variability and primary production

    NASA Astrophysics Data System (ADS)

    Arrigo, Kevin R.; Worthen, Denise L.; Robinson, Dale H.

    2003-07-01

    A model of the Ross Sea pelagic ecosystem has been developed by incorporating biological and nutrient dynamics into an ocean general circulation model. Surface heat and salt fluxes are calculated in the model using sea ice concentrations that are specified daily using the 20 year climatology derived from passive microwave satellite data. Surface spectral irradiance is calculated and propagated through both the water column and the sea ice. The biological state variables include two phytoplankton groups (diatoms and Phaeocystis antarctica), two nutrients (NO3 and Fe), detritus, and zooplankton. Nutrients are supplied to the sea surface from upwelling of nutrient-rich deep waters, and in the case of Fe, from melting sea ice and snow which have accumulated aeolian-derived Fe during the preceding autumn and winter. Phytoplankton growth rate is computed as a function of light or nutrient limitation. The model is able to accurately simulate the temporal evolution of the two well-described phytoplankton blooms that dominate the southwestern Ross Sea: the diatom bloom in the shallow mixed layer of the western continental shelf (including Terra Nova Bay) and the P. antarctica bloom in the more deeply mixed Ross Sea polynya region. The simulated temporal progression of both phytoplankton blooms as well as their magnitude of primary production are in good agreement with time series estimates made using satellite ocean color data as validated by in situ observations. Model results suggest that Fe availability controls annual primary production in the Ross Sea, with only about two thirds of the available macronutrients in surface waters being consumed during the course of the bloom, but that Fe has little role in determining phytoplankton community composition. Rather, the taxonomic composition of the phytoplankton blooms is determined by the differential responses of shade-adapted P. antarctica and high light-adapted diatoms to the different mixing (and hence light) regimes

  4. Determination of embryonic temperature profiles and eggshell water vapor conductance constants in incubating Ross x Ross 708 broiler hatching eggs using temperature transponders.

    PubMed

    Pulikanti, R; Peebles, E D; Zhai, W; Gerard, P D

    2012-01-01

    The comprehensive profiles of the internal and external temperatures of embryonated Ross × Ross 708 broiler hatching eggs during incubation were determined using temperature transponders, and eggshell water vapor conductance (G(H2O)), specific G(H2O) (g(H2O); G(H2O) adjusted to a 100 g set egg weight basis), and G(H2O) constants (K(H2O)) were calculated. On each of 8 replicate tray levels of an incubator, 2 nonembryonated and 4 embryonated eggs were each implanted with a transponder on d 10.5 of incubation for the determination of internal (air cell) temperatures of nonembryonated (T(nem)) and embryonated (T(emb)) eggs, respectively. In addition, 2 water-filled vials, each containing a transponder, were used on each tray level for the determination of the external microenvironment temperatures (T(ext)) of the embryonated and nonembryonated eggs. Between 10.5 and 18 d of incubation, incubator data logger temperatures were determined every 5 min; and incubator dry bulb temperature, T(ext), T(nem), T(emb), and the difference between T(emb) and T(nem) (T) were determined every 12 h. Over the days of incubation, regression coefficients for T(emb) and T were positive, whereas the regression coefficient for T(nem) was negative. There was a significant day of incubation × type of temperature measurement (T(ext), T(nem), and T(emb)) interaction for temperature. Between 13 and 18 d of incubation, mean values of T(emb) readings that were recorded every 12 h were consistently higher than those of T(ext) and T(nem), indicating the importance of air cell transponder implantation for the efficient estimation of broiler embryo temperature. Furthermore, mean values of the percentage of daily incubational egg weight loss, G(H2O), g(H2O), and K(H2O) of the embryonated eggs were 0.54 ± 0.019%, 14.4 ± 0.56 mg of H₂O/d per Torr, 25.0 ± 0.96 mg of H₂O/d per Torr per 100 g, and 5.20 ± 0.205, respectively. The results suggest that transponders may be implanted in the air cells of

  5. Occurrence and turnover of DMSP and DMS in deep waters of the Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Rellinger, Alison N.; Kiene, Ronald P.; del Valle, Daniela A.; Kieber, David J.; Slezak, Doris; Harada, Hyakubun; Bisgrove, John; Brinkley, Jordan

    2009-05-01

    High concentrations of the phytoplankton metabolite dimethylsulfoniopropionate (DMSP) and its degradation product dimethylsulfide (DMS) are associated with blooms of Phaeocystis antarctica in the Ross Sea, Antarctica. Episodic and rapid vertical export of Phaeocystis biomass to deep water has been reported for the Ross Sea, therefore we examined the distribution and microbial consumption rates of DMSP and DMS throughout the sub-euphotic water column. Total DMSP (dissolved+particulate; DMSPt) was present at 0.5-22 nM at depths between 70 and 690 m during both the early bloom (November) and the late bloom (January). Sub-euphotic peaks of DMSP were sometimes associated with mid-water temperature maxima, and elevated DMSP below 70 m was found mainly in water masses characterized as Modified Circumpolar Deep Water or Antarctic Shelf Water. Overall, 50-94% of the integrated water-column DMSPt was found below the euphotic zone. At one station during the early bloom, local maxima of DMSPt (14 nM) and DMS (20 nM) were observed between 113 and 240 m and these maxima corresponded with high chlorophyll a concentrations, P. antarctica cell numbers, and Fv/Fm (the quantum yield of photosystem II). During the late bloom, a sub-euphotic maximum of DMSPt (15.8 nM) at 250 m cooccurred with peaks of chlorophyll a concentration, DMSP lyase activity, bacterial production and dissolved DMSP consumption rates. DMSP turnover contributed ˜12% of the bacterial carbon demand between 200 and 400 m. DMS concentrations peaked at 286 m but the maximum concentration (0.42 nM) was far lower than observed during the early bloom, probably because of relatively rapid biological consumption of DMS (1-3 turnovers per day) which, in turn, contributed to elevated dissolved dimethylsulfoxide (DMSO) concentrations. Relatively stable DMSPt distributions at some sites suggest that rapid sinking of Phaeocystis biomass is probably not the major mechanism responsible for mesopelagic DMSP accumulations. Rather

  6. Distribution, abundance and acoustic properties of Antarctic silverfish ( Pleuragramma antarcticum) in the Ross Sea

    NASA Astrophysics Data System (ADS)

    O'Driscoll, Richard L.; Macaulay, Gavin J.; Gauthier, Stéphane; Pinkerton, Matt; Hanchet, Stuart

    2011-03-01

    Antarctic silverfish ( Pleuragramma antarcticum) is a key link between plankton and the community of top predators in the shelf waters of the Ross Sea. In spite of their abundance and important role in Antarctic food chains, very little is known of many ecological and biological aspects of this species. A combined trawl and acoustic survey of silverfish was carried out on the western Ross Sea shelf during the New Zealand International Polar Year Census of Antarctic Marine Life research voyage on R.V. Tangaroa in February-March 2008. Multi-frequency acoustic data (12, 38, 70, and 120 kHz) allowed discrimination of silverfish marks from those of krill and other associated species. Mark identification was achieved using targeted midwater trawls. Additional midwater and demersal trawls were carried out at randomly selected locations over the shelf as part of the core biodiversity survey. Silverfish were widely distributed over the Ross Sea shelf. Adult silverfish tended to form layers at 100-400 m depth and were sometimes present close to the bottom, where they were frequently caught in demersal trawls shallower than 500 m. A weak layer at about 80 m depth was associated with juvenile silverfish of 50-80 mm standard length. Acoustic backscatter strength from both silverfish and krill marks increased with increasing frequency (i.e., was highest at 120 kHz), which is characteristic of species without an air-filled swimbladder. Acoustic target strengths (TS) for silverfish at 12, 18, 38, 70, and 120 kHz were estimated from anatomically detailed scattering models based on computed tomography (CT) scans of frozen specimens. The relationship between TS and fish length at 38 kHz was sensitive to estimates of density and sound speed contrast within the fish, especially for small specimens (less than 110 mm SL). Our best estimate of the acoustic biomass of silverfish in the study area was 592 000 t (95% confidence interval 326 000-866 000 t). However, the biomass of juvenile

  7. Little Ice Age climate and oceanic conditions of the Ross Sea, Antarctica from a coastal ice core record

    NASA Astrophysics Data System (ADS)

    Rhodes, R. H.; Bertler, N. A. N.; Baker, J. A.; Steen-Larsen, H. C.; Sneed, S. B.; Morgenstern, U.; Johnsen, S. J.

    2012-07-01

    Increasing paleoclimatic evidence suggests that the Little Ice Age (LIA) was a global climate change event. Understanding the forcings and associated climate system feedbacks of the LIA is made difficult by the scarcity of Southern Hemisphere paleoclimate records. We use a new glaciochemical record of a coastal ice core from Mt. Erebus Saddle, Antarctica, to reconstruct atmospheric and oceanic conditions in the Ross Sea sector of Antarctica over the past five centuries. The LIA is identified in stable isotope (δD) and lithophile element records, which respectively demonstrate that the region experienced 1.6 ± 1.4 °C cooler average temperatures prior to 1850 AD than during the last 150 yr and strong (>57 m s-1) prevailing katabatic winds between 1500 and 1800 AD. Al and Ti concentration increases of an order of magnitude (>120 ppb Al) are linked to enhanced aeolian transport of complex silicate minerals and represent the strongest katabatic wind events of the LIA. These events are associated with three 12-30 yr intervals of cooler temperatures at ca. 1690 AD, 1770 AD and 1840 AD. Furthermore, ice core concentrations of the biogenic sulphur species MS- suggest that biological productivity in the Ross Sea polynya was ~80% higher prior to 1875 AD than at any subsequent time. We propose that cooler Antarctic temperatures promoted stronger katabatic winds across the Ross Ice Shelf, resulting in an enlarged Ross Sea polynya during the LIA.

  8. A New Analysis of the Two Classical ZZ Ceti White Dwarfs GD 165 and Ross 548. II. Seismic Modeling

    NASA Astrophysics Data System (ADS)

    Giammichele, N.; Fontaine, G.; Brassard, P.; Charpinet, S.

    2016-03-01

    We present the second of a two-part seismic analysis of the bright, hot ZZ Ceti stars GD 165 and Ross 548. In this second part, we report the results of detailed searches in parameter space for identifying an optimal model for each star that can account well for the observed periods, while being consistent with the spectroscopic constraints derived in our first paper. We find optimal models for each target that reproduce the six observed periods well within ∼0.3% on the average. We also find that there is a sensitivity on the core composition for Ross 548, while there is practically none for GD 165. Our optimal model of Ross 548, with its thin envelope, indeed shows weight functions for some confined modes that extend relatively deep into the interior, thus explaining the sensitivity of the period spectrum on the core composition in that star. In contrast, our optimal seismic model of its spectroscopic sibling, GD 165 with its thick envelope, does not trap/confine modes very efficiently, and we find weight functions for all six observed modes that do not extend into the deep core, hence accounting for the lack of sensitivity in that case. Furthermore, we exploit after the fact the observed multiplet structure that we ascribe to rotation. We are able to map the rotation profile in GD 165 (Ross 548) over the outermost ∼20% (∼5%) of its radius, and we find that the profile is consistent with solid-body rotation.

  9. 78 FR 19330 - Supplemental Environmental Impact Statement for the Ross In-Situ Uranium Recovery Project in...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-29

    ..., operation, aquifer restoration, and decommissioning of an in situ leach uranium milling facility (also known... applicant proposes the construction, operation, aquifer restoration, and decommissioning of an ISR facility... construction, operation, aquifer restoration, and decommissioning of the proposed Ross Project. The NRC...

  10. 75 FR 31805 - Announcement of Funding Awards for the Resident Opportunity and Self-Sufficiency (ROSS)-Service...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-04

    ... 36602. Jonesboro Urban Renewal & Housing 330 Union, Jonesboro, AR 152,630 Authority. 72401. Little Rock... URBAN DEVELOPMENT Announcement of Funding Awards for the Resident Opportunity and Self-Sufficiency (ROSS... and Urban Development Reform Act of 1989, this announcement notifies the public of funding...

  11. 78 FR 56944 - Strata Energy, Inc. (Ross In Situ Recovery Uranium Project); Notice of Atomic Safety and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-16

    ... COMMISSION Strata Energy, Inc. (Ross In Situ Recovery Uranium Project); Notice of Atomic Safety and Licensing Board Reconstitution Pursuant to 10 CFR 2.313(c) and 2.321(b), the Atomic Safety and Licensing Board... 2013. E. Roy Hawkens, Chief Administrative Judge, Atomic Safety and Licensing Board Panel. BILLING...

  12. An examination of the role of colonial Phaeocystis antarctica in the microbial food web of the Ross Sea

    EPA Science Inventory

    The extensive buildup of phytoplankton biomass in the Ross Sea conflicts with the view that high rates of herbivory occur in all regions of the Southern Ocean. Nano- and microplanktonic consumers comprise a significant fraction of total plankton biomass; however, the importance o...

  13. Men of Good Will: The Religious Education Association, J. Elliot Ross, and the National Conference of Jews and Christians

    ERIC Educational Resources Information Center

    Nolan, Lucinda A.

    2009-01-01

    An impetus of the Religious Education Association (REA) toward becoming an actively intercultural and interreligious agency emerged in the third decade of its existence. This article explores this period through an examination of the involvement of the REA members, Father John Elliot Ross and others (1884-1946) in a series of seminars conducted by…

  14. Correlated measurements of ozone and particulates in the Ross Island region, Antarctica

    NASA Astrophysics Data System (ADS)

    Kalnajs, Lars E.; Avallone, Linnea M.; Toohey, Darin W.

    2013-12-01

    gases, submicron particle size distributions, and bulk filterable halogen content were measured on Ross Island, Antarctica, in austral spring 2007. During several surface level, partial ozone depletion events, enhanced submicron particle concentrations, and changes in filterable halogens were observed. These events were characterized by ozone depletions of 5-15 ppbv for durations between 6 and 48 h and associated with threefold-to-fourfold increases in submicron particle mass (PM1.0) over backgrounds of approximately 100 ng m-3. Peak particle number densities were centered on a mode at 500-600 nm in diameter, which is consistent with wintertime sea-salt aerosol size distributions. Filterable chloride also increased during these events, consistent with aerosol being of oceanic origin. Ozone depletion and particle enhancement events were accompanied by increasing temperatures and winds, suggesting that halogen-containing aerosol is generated from windblown snow and brine from the snow pack or sea ice near the ice edge.

  15. The Cambrian Ross Orogeny in northern Victoria Land (Antarctica) and New Zealand: A synthesis

    USGS Publications Warehouse

    Federico, L.; Capponi, G.; Crispini, L.; Bradshaw, J.D.

    2007-01-01

    In the Cambrian, the paleo-Pacific margin of the Gondwana supercontinent included East Antarctica, Australia, Tasmania and New Zealand and was affected by themajor Ross-Delamerian Orogeny. In Antarctica, evidence suggests that this resulted from oblique subduction and that in northern Victoria Land it was accompanied by the opening and subsequent closure of a back-arc basin. Comparison of the type and timing of sedimentary, magmatic and metamorphic events in areas noted above shows strong similarities between northern Victoria Land and New Zealand. In both regions Middle Cambrian volcanites are interpreted as arc/back-arc assemblages produced by west-directed subduction; sediments interbedded with the volcanites show provenance both from the arc and from the Gondwana margin and therefore place the basin close to the continent. Back-arc closure in the Late Cambrian was likely accomplished through a second subduction system

  16. Episodic rifting of phanerozoic rocks in the victoria land basin, Western ross sea, antarctica.

    PubMed

    Cooper, A K; Davey, F J

    1985-09-13

    Multichannel seismic-reflection data show that the Victoria Land-basin, unlike other sedimentary basins in the Ross Sea, includes a rift-depression 15 to 25 kilometers wide that parallels the Transantarctic Mountains and contains up to 12 kilometers of possible Paleozoic to Holocene age sedimentary rocks. An unconformity separates the previously identified Cenozoic sedimentary section from the underlying strata of possible Mesozoic and Paleozoic age. Late Cenozoic volcanic rocks intrude into the entire section along the eastern flank of the basin. The Victoria Land basin is probably part of a more extensive rift system that has been active episodically since Paleozoic time. Inferred rifting and basin subsidence during Mesozoic and Cenozoic time may be associated with regional crustal extension and uplift of the nearby Transantarctic Mountains. PMID:17753283

  17. Increase in penguin populations during the Little Ice Age in the Ross Sea, Antarctica

    PubMed Central

    Hu, Qi-Hou; Sun, Li-Guang; Xie, Zhou-Qing; Emslie, Steven D.; Liu, Xiao-Dong

    2013-01-01

    Penguins are an important seabird species in Antarctica and are sensitive to climate and environmental changes. Previous studies indicated that penguin populations increased when the climate became warmer and decreased when it became colder in the maritime Antarctic. Here we determined organic markers in a sediment profile collected at Cape Bird, Ross Island, high Antarctic, and reconstructed the history of Adélie penguin colonies at this location over the past 700 years. The region transformed from a seal to a penguin habitat when the Little Ice Age (LIA; 1500–1800 AD) began. Penguins then became the dominant species. Penguin populations were the highest during ca. 1490 to 1670 AD, a cold period, which is contrary to previous results in other regions much farther north. Different responses to climate change may occur at low latitudes and high latitudes in the Antarctic, even if for same species. PMID:23969993

  18. High basal melting forming a channel at the grounding line of Ross Ice Shelf, Antarctica

    NASA Astrophysics Data System (ADS)

    Marsh, Oliver J.; Fricker, Helen A.; Siegfried, Matthew R.; Christianson, Knut; Nicholls, Keith W.; Corr, Hugh F. J.; Catania, Ginny

    2016-01-01

    Antarctica's ice shelves are thinning at an increasing rate, affecting their buttressing ability. Channels in the ice shelf base unevenly distribute melting, and their evolution provides insight into changing subglacial and oceanic conditions. Here we used phase-sensitive radar measurements to estimate basal melt rates in a channel beneath the currently stable Ross Ice Shelf. Melt rates of 22.2 ± 0.2 m a-1 (>2500% the overall background rate) were observed 1.7 km seaward of Mercer/Whillans Ice Stream grounding line, close to where subglacial water discharge is expected. Laser altimetry shows a corresponding, steadily deepening surface channel. Two relict channels to the north suggest recent subglacial drainage reorganization beneath Whillans Ice Stream approximately coincident with the shutdown of Kamb Ice Stream. This rapid channel formation implies that shifts in subglacial hydrology may impact ice shelf stability.

  19. High-paleolatitude late cretaceous paleotemperatures: New data from James Ross Island, Antarctica

    SciTech Connect

    Pirrie, D. ); Marshall, J.D. )

    1990-01-01

    Oxygen-isotope analysis of well-preserved macrofossils from the Santonian-Campanian of James Ross Island and the Maastrichtian of Vega Island, Antarctica, indicates that cool high-paleolatitude temperatures prevailed during the Late Cretaceous and suggests that cooling occurred between the Santonian-Campanian and the Maastrichtian. Although more than 50% of the material showed diagenetic alteration, 52 unaltered aragonite and calcite samples were analyzed. Mean {delta}{sup 18}O and calculated paleotemperature values were {minus}0.23{per thousand} and 13.6 C, respectively, for the Santonian-Campanian, and 0.66{per thousand} and 11.7 C, respectively, for the Masstrichtian. In conjunction with recent Late Cretaceous paleoclimatic data from high northern paleolatitudes, these data indicate the presence of cool polar regions with broad climatic zonation during the late Cretaceous. This may have partly controlled faunal distributions.

  20. Changes in sea-ice cover and temperature in the Western Ross Sea during the Holocene

    NASA Astrophysics Data System (ADS)

    Fleury, Sophie; Kim, Jung-Hyun; Gal, Jong-Ku; Mezgec, Karin; Belt, Simon; Smik, Lukas; Stenni, Barbara; Melis, Romana; Crosta, Xavier; Shin, Kyung-Hoon

    2016-04-01

    Although changes in sea-ice cover contribute to global climatic variations, they are poorly constrained for periods earlier than the last decades. More records are especially required around Antarctica, where the formation of Antarctic Bottom Waters participates to global thermohaline circulation. However, this region provided only a few marine sediment cores spanning the entire Holocene, especially because of generally low sedimentation rates. This study focuses on marine sediment core ANTA99-CJ5 (73°49'S; 175°39'E), located in the open sea ice zone (OSIZ) of the western Ross Sea. We analyzed several lipid biomarkers: highly branched isoprenoids (HBIs), sterols, diols and GDGTs. The combination of several biomarkers and the comparison of these results with a diatom record previously published on the same core enabled us to trace past changes in temperatures as well as in sea-ice condition over the last 11,600 years.

  1. Episodic rifting of phanerozoic rocks in the Victoria Land basin, Western Ross Sea, Antarctica

    USGS Publications Warehouse

    Cooper, A. K.; Davey, F.J.

    1985-01-01

    Multichannel seismic-reflection data show that the Victoria Land basin, unlike other sedimentary basins in the Ross Sea, includes a rift-depression 15 to 25 kilometers wide that parallels the Transantarctic Mountains and contains up to 12 kilometers of possible Paleozoic to Holocene age sedimentary rocks. An unconformity separates the previously identified Cenozoic sedimentary section from the underlying strata of possible Mesozoic and Paleozoic age. Late Cenozoic volcanic rocks intrude into the entire section along the eastern flank of the basin. The Victoria Land basin is probably part of a more extensive rift system that has been active episodically since Paleozoic time. Inferred rifting and basin subsidence during Mesozoic and Cenozoic time may be associated with regional crustal extension and uplift of the nearby Transantarctic Mountains.

  2. High-resolution airborne gravity imaging over James Ross Island (West Antarctica)

    USGS Publications Warehouse

    Jordan, T.A.; Ferraccioli, F.; Jones, P.C.; Smellie, J.L.; Ghidella, M.; Corr, H. F. J.; Zakrajsek, A.F.

    2007-01-01

    James Ross Island (JRI) exposes a Miocene-Recent alkaline basaltic volcanic complex that developed in a back-arc, east of the northern Antarctic Peninsula. JRI has been the focus of several geological studies because it provides a window on Neogene magmatic processes and paleoenvironments. However, little is known about its internal structure. New airborne gravity data were collected as part of the first high-resolution aerogeophysical survey flown over the island and reveal a prominent negative Bouguer gravity anomaly over Mt Haddington. This is intriguing as basaltic volcanoes are typically associated with positive Bouguer anomalies, linked to underlying mafic intrusions. The negative Bouguer anomaly may be associated with a hitherto unrecognised low-density sub-surface body, such as a breccia-filled caldera, or a partially molten magma chamber.

  3. STS-55 MS1/PLC Ross monitors Payload Specialist Walter's Anthrorack activity

    NASA Technical Reports Server (NTRS)

    1993-01-01

    STS-55 German Payload Specialist 1 Ulrich Walter breathes into Rack 9 Anthrorack (AR) (Human Physiology Laboratory) device for Pulmonary Perfusion and Ventilation During Rest and Exercise experiment while working inside the Spacelab Deutsche 2 (SL-D2) science module aboard the Earth-orbiting Columbia, Orbiter Vehicle (OV) 102. Seated on the bicycle ergometer, Walter utilizes the respiratory monitoring system, part of a broad battery of experiments designed to investigate human physiology under microgravity conditions. In the background, Mission Specialist 1 (MS1) and Payload Commander (PLC) Jerry L. Ross monitors Walter's activity. Walter represents the German Aerospace Research Establishment (DLR) on the 10-day SL-D2 mission. Visible on the aft end cone are a fire extinguisher and the Crew Telesupport Experiment (CTE) Macintosh portable computer mounted on an adjustable work platform.

  4. Iron limitation of a springtime bacterial and phytoplankton community in the ross sea: implications for vitamin b(12) nutrition.

    PubMed

    Bertrand, Erin M; Saito, Mak A; Lee, Peter A; Dunbar, Robert B; Sedwick, Peter N; Ditullio, Giacomo R

    2011-01-01

    The Ross Sea is home to some of the largest phytoplankton blooms in the Southern Ocean. Primary production in this system has previously been shown to be iron limited in the summer and periodically iron and vitamin B(12) colimited. In this study, we examined trace metal limitation of biological activity in the Ross Sea in the austral spring and considered possible implications for vitamin B(12) nutrition. Bottle incubation experiments demonstrated that iron limited phytoplankton growth in the austral spring while B(12), cobalt, and zinc did not. This is the first demonstration of iron limitation in a Phaeocystis antarctica-dominated, early season Ross Sea phytoplankton community. The lack of B(12) limitation in this location is consistent with previous Ross Sea studies in the austral summer, wherein vitamin additions did not stimulate P. antarctica growth and B(12) was limiting only when bacterial abundance was low. Bottle incubation experiments and a bacterial regrowth experiment also revealed that iron addition directly enhanced bacterial growth. B(12) uptake measurements in natural water samples and in an iron fertilized bottle incubation demonstrated that bacteria serve not only as a source for vitamin B(12), but also as a significant sink, and that iron additions enhanced B(12) uptake rates in phytoplankton but not bacteria. Additionally, vitamin uptake rates did not become saturated upon the addition of up to 95 pM B(12). A rapid B(12) uptake rate was observed after 13 min, which then decreased to a slower constant uptake rate over the next 52 h. Results from this study highlight the importance of iron availability in limiting early season Ross Sea phytoplankton growth and suggest that rates of vitamin B(12) production and consumption may be impacted by iron availability. PMID:21886638

  5. Regional compilation and analysis of aeromagnetic anomalies for the Transantarctic Mountains Ross Sea sector of the Antarctic

    NASA Astrophysics Data System (ADS)

    Chiappini, M.; Ferraccioli, F.; Bozzo, E.; Damaske, D.

    2002-03-01

    Magnetic observations over the area of the Transantarctic Mountains (TAM) and the Ross Sea have been compiled into a digital database that furnishes a new regional scale view of the magnetic anomaly crustal field in this key sector of the Antarctic continent. This compilation is a component of the ongoing IAGA/SCAR Antarctic Digital Magnetic Anomaly Project (ADMAP). The aeromagnetic surveys total 115 000 line km, and are distributed across the Victoria Land sector of the TAM, the Ross Sea, and Marie Byrd Land. The magnetic campaigns were performed within the framework of the national and international Italian-German-US Antarctic research programs and conducted with differing specifications during nine field seasons from 1971 until 1997. Generally flight line spacing was less than 5 km while survey altitude varied from about 610 to 4000 m above sea level for barometric surveys and was equal to 305 m above topography for the single draped survey. Reprocessing included digitizing the old contour data, improved levelling by means of microlevelling in the frequency domain, and re-reduction to a common reference field based on the DGRF90 model. A multi-frequency grid procedure was then applied to obtain a coherent and merged total intensity magnetic anomaly map. The shaded relief map covers an area of approximately 380 000 km 2. This new compilation provides a regional image of the location and spatial extent of the Cenozoic alkaline magmatism related to the TAM-Ross Sea rift, Jurassic tholeiites, and crustal segments of the Early Palaeozoic magmatic arc. A linear, approximately 100-km wide and 600-km long Jurassic rift-like structure is newly identified. Magnetic fabric in the Ross Sea rift often matches seismically imaged Cenozoic fault arrays. Major buried onshore pre-rift fault zones, likely inherited from the Ross Orogen, are also delineated. These faults may have been reactivated as strike-slip belts that segmented the TAM into various crustal blocks.

  6. Iron Limitation of a Springtime Bacterial and Phytoplankton Community in the Ross Sea: Implications for Vitamin B12 Nutrition

    PubMed Central

    Bertrand, Erin M.; Saito, Mak A.; Lee, Peter A.; Dunbar, Robert B.; Sedwick, Peter N.; DiTullio, Giacomo R.

    2011-01-01

    The Ross Sea is home to some of the largest phytoplankton blooms in the Southern Ocean. Primary production in this system has previously been shown to be iron limited in the summer and periodically iron and vitamin B12 colimited. In this study, we examined trace metal limitation of biological activity in the Ross Sea in the austral spring and considered possible implications for vitamin B12 nutrition. Bottle incubation experiments demonstrated that iron limited phytoplankton growth in the austral spring while B12, cobalt, and zinc did not. This is the first demonstration of iron limitation in a Phaeocystis antarctica-dominated, early season Ross Sea phytoplankton community. The lack of B12 limitation in this location is consistent with previous Ross Sea studies in the austral summer, wherein vitamin additions did not stimulate P. antarctica growth and B12 was limiting only when bacterial abundance was low. Bottle incubation experiments and a bacterial regrowth experiment also revealed that iron addition directly enhanced bacterial growth. B12 uptake measurements in natural water samples and in an iron fertilized bottle incubation demonstrated that bacteria serve not only as a source for vitamin B12, but also as a significant sink, and that iron additions enhanced B12 uptake rates in phytoplankton but not bacteria. Additionally, vitamin uptake rates did not become saturated upon the addition of up to 95 pM B12. A rapid B12 uptake rate was observed after 13 min, which then decreased to a slower constant uptake rate over the next 52 h. Results from this study highlight the importance of iron availability in limiting early season Ross Sea phytoplankton growth and suggest that rates of vitamin B12 production and consumption may be impacted by iron availability. PMID:21886638

  7. Antarctic Ice Sheet dynamics in the Ross Sea during the Early to Middle Miocene

    NASA Astrophysics Data System (ADS)

    Levy, Richard; Harwood, David; Florindo, Fabio; DeConto, Robert; Golledge, Nicholas; Hoffmann, Stefan; Kuhn, Gerhard; McKay, Robert; Naish, Timothy; Pollard, David; Sangiorgi, Francesca; von Eynatten, Hilmar

    2015-04-01

    A 1138-meter sediment core (AND-2A) recovered from the Southern McMurdo Sound sector of the Ross Sea comprises a near-continuous record of Antarctic climate and ice sheet variability through the Early to early Middle Miocene (20.2 to 14.5 million years ago), including an interval of inferred sustained global warmth known as the Miocene Climatic Optimum (MCO). The record preserves 55 sedimentary sequences that reflect cycles of glacial advance and retreat. A new analysis of proxy environmental data from the AND-2A core, and synthesis with regional geological information, show that the early to middle Miocene Antarctic climate ranged from cold polar conditions, similar to Antarctica during the Holocene, to those that characterise modern sub-polar environments. Four disconformities that punctuate the sedimentary sequence coincide with regionally mapped seismic discontinuities and reflect transient expansion of marine-based ice across the Ross Sea. The timing of these major marine-based ice sheet advances correlates with shifts in highly-resolved deep sea isotope records and major drops in eustatic sea-level indicating the global nature of these events. In contrast, three distinct intervals in the core indicate that this high latitude site was periodically influenced by an ice sheet margin that had retreated beyond the coastline. These relatively large-scale changes in climate and ice sheet extent occurred under atmospheric carbon dioxide concentrations that generally varied between 300 to 500 ppm. Therefore, our reconstructions suggest that Antarctica's climate and ice sheets were sensitive to modest changes in greenhouse gas forcing and support previous studies, which indicate that marine-based portions of the WAIS and EAIS can retreat under climatic conditions that were similar to those projected for our future under current levels of atmospheric CO2.

  8. Ross Sea Polynyas: Response of Ice Concentration Retrievals to Large Areas of Thin Ice

    NASA Technical Reports Server (NTRS)

    Kwok, R.; Comiso, J. C.; Martin, S.; Drucker, R.

    2007-01-01

    For a 3-month period between May and July of 2005, we examine the response of the Advanced Microwave Scanning Radiometer (AMSR-E) Enhanced NASA Team 2 (NT2) and AMSR-E Bootstrap (ABA) ice concentration algorithms to large areas of thin ice of the Ross Sea polynyas. Coincident Envisat Synthetic Aperture Radar (SAR) coverage of the region during this period offers a detailed look at the development of the polynyas within several hundred kilometers of the ice front. The high-resolution imagery and derived ice motion fields show bands of polynya ice, covering up to approximately 105 km(sup 2) of the Ross Sea, that are associated with wind-forced advection. In this study, ice thickness from AMSR-E 36 GHz polarization information serves as the basis for examination of the response. The quality of the thickness of newly formed sea ice (<10 cm) from AMSR-E is first assessed with thickness estimates derived from ice surface temperatures from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. The effect of large areas of thin ice in lowering the ice concentration estimates from both NT2/ABA approaches is clearly demonstrated. Results show relatively robust relationships between retrieved ice concentrations and thin ice thickness estimates that differ between the two algorithms. These relationships define the approximate spatial coincidence of ice concentration and thickness isopleths. Using the 83% (ABA) and 91% (NT2) isopleths as polynya boundaries, we show that the computed coverage compares well with that using the estimated 10-cm thickness contour. The thin ice response characterized here suggests that in regions with polynyas, the retrieval results could be used to provide useful geophysical information, namely thickness and coverage.

  9. Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA

    NASA Astrophysics Data System (ADS)

    Rainsford, A.; Soave, K.; Costolo, R.; Kudler, J.; Emunah, M.; Hatfield, J.; Kiyasu, J.

    2015-12-01

    Alina Rainsford, Kathy Soave, Julia Kudler, Jane Hatfield, Melea Emunah, Rose Costelo, Jenna Kiyasu, Amy Dean and Sustainable Seas Monitoring Project, Branson School, Ross, CA, United States, Farallones Marine Sanctuary Association, San Francisco, CA, United StatesAbstract:The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of this student-run project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program & Experiential Training for Students). Each fall student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal monitoring techniques, and history of the sanctuary. Students identify and count key invertebrate and algae species along two permanent transects and, using randomly determined points, within two permanent 200 m2 areas, in fall, winter, and late spring. Using data from the previous years, we will compare population densities, seasonal abundance and long-term population trends of key algal and invertebrate species, including Tegula funebralis, Anthopluera elegantissima, Cladophora sp. and Fucus sp.. Future analyses and investigations will include intertidal abiotic factors (including water temperature, pH and human foot-traffic) to enhance insights into the Duxbury Reef ecosystem, in particular, the high

  10. Environment at the Grounding Zone of the Whillans Ice Stream-Ross Ice Shelf, West Antarctica

    NASA Astrophysics Data System (ADS)

    Hodson, T. O.; Powell, R. D.; Mikucki, J.; Scherer, R. P.; Tulaczyk, S. M.; Coenen, J. J.; Puttkammer, R.; Branecky, C.

    2015-12-01

    Grounding zones where grounded ice sheets transition to floating ice shelves, are the primary gateways through which the Antarctic Ice Sheet loses mass to the ocean. In these environments, ice, ocean, meltwater and sediment meet and interact, influencing both the ice sheet and ocean circulation beneath the ice shelf. Here, we report on conditions near the grounding zone of the Whillans Ice Stream, which feeds into the Ross Ice Shelf. Cameras and instruments lowered through an access borehole to the ocean cavity beneath the ice shelf found a 10m-thick water column comprising an upper layer of colder ice shelf water formed from mixing between meltwater with the lower layer of warmer higher salinity shelf water. This style of stratification is typical of large ice shelves, but it was uncertain whether it existed so near the grounding zone, where stronger tidal currents and/or strong subglacial stream discharges could mix the water column. Salinity and temperature of the water suggest it formed from sea ice production in the Western Ross Sea, with minimal modification beneath the ice shelf. This source region is distinct from waters previously observed at the nearby J-9 borehole, illustrating the importance of the sub-ice shelf bathymetry in steering circulation between the ocean and the grounding zone. Preliminary data suggest an active exchange of heat and nutrients between the grounding zone and the open ocean, despite being separated by 600km. Thus life found near the grounding line is probably not an isolated oasis, but may instead be part of a much broader ecosystem that spans the ice shelf. Although sea ice formation presently maintains water in the sub-ice shelf cavity near the surface freezing point, buffering many larger ice shelves from gradual ocean warming, these findings suggest that even grounding zones of extensive ice shelves may respond quickly to abrupt changes in ocean circulation, such as that observed in the Amundsen Sea.

  11. Ocean variability contributing to basal melt rate near the ice front of Ross Ice Shelf, Antarctica

    NASA Astrophysics Data System (ADS)

    Arzeno, Isabella B.; Beardsley, Robert C.; Limeburner, Richard; Owens, Breck; Padman, Laurie; Springer, Scott R.; Stewart, Craig L.; Williams, Michael J. M.

    2014-07-01

    Basal melting of ice shelves is an important, but poorly understood, cause of Antarctic ice sheet mass loss and freshwater production. We use data from two moorings deployed through Ross Ice Shelf, ˜6 and ˜16 km south of the ice front east of Ross Island, and numerical models to show how the basal melting rate near the ice front depends on sub-ice-shelf ocean variability. The moorings measured water velocity, conductivity, and temperature for ˜2 months starting in late November 2010. About half of the current velocity variance was due to tides, predominantly diurnal components, with the remainder due to subtidal oscillations with periods of a few days. Subtidal variability was dominated by barotropic currents that were large until mid-December and significantly reduced afterward. Subtidal currents were correlated between moorings but uncorrelated with local winds, suggesting the presence of waves or eddies that may be associated with the abrupt change in water column thickness and strong hydrographic gradients at the ice front. Estimated melt rate was ˜1.2 ± 0.5 m a-1 at each site during the deployment period, consistent with measured trends in ice surface elevation from GPS time series. The models predicted similar annual-averaged melt rates with a strong annual cycle related to seasonal provision of warm water to the ice base. These results show that accurately modeling the high spatial and temporal ocean variability close to the ice-shelf front is critical to predicting time-dependent and mean values of meltwater production and ice-shelf thinning.

  12. Diversity and distribution of deep-sea shrimps in the Ross Sea region of Antarctica.

    PubMed

    Basher, Zeenatul; Bowden, David A; Costello, Mark J

    2014-01-01

    Although decapod crustaceans are widespread in the oceans, only Natantia (shrimps) are common in the Antarctic. Because remoteness, depth and ice cover restrict sampling in the South Ocean, species distribution modelling is a useful tool for evaluating distributions. We used physical specimen and towed camera data to describe the diversity and distribution of shrimps in the Ross Sea region of Antarctica. Eight shrimp species were recorded: Chorismus antarcticus; Notocrangon antarcticus; Nematocarcinus lanceopes; Dendrobranchiata; Pasiphaea scotiae; Pasiphaea cf. ledoyeri; Petalidium sp., and a new species of Lebbeus. For the two most common species, N. antarcticus and N. lanceopes, we used maximum entropy modelling, based on records of 60 specimens and over 1130 observations across 23 sites in depths from 269 m to 3433 m, to predict distributions in relation to environmental variables. Two independent sets of environmental data layers at 0.05° and 0.5° resolution respectively, showed how spatial resolution affected the model. Chorismus antarcticus and N. antarcticus were found only on the continental shelf and upper slopes, while N. lanceopes, Lebbeus n. sp., Dendrobranchiata, Petalidium sp., Pasiphaea cf. ledoyeri, and Pasiphaea scotiae were found on the slopes, seamounts and abyssal plain. The environmental variables that contributed most to models for N. antarcticus were depth, chlorophyll-a concentration, temperature, and salinity, and for N. lanceopes were depth, ice concentration, seabed slope/rugosity, and temperature. The relative ranking, but not the composition of these variables changed in models using different spatial resolutions, and the predicted extent of suitable habitat was smaller in models using the finer-scale environmental layers. Our modelling indicated that shrimps were widespread throughout the Ross Sea region and were thus likely to play important functional role in the ecosystem, and that the spatial resolution of data needs to be

  13. Diversity and Distribution of Deep-Sea Shrimps in the Ross Sea Region of Antarctica

    PubMed Central

    Basher, Zeenatul; Bowden, David A.; Costello, Mark J.

    2014-01-01

    Although decapod crustaceans are widespread in the oceans, only Natantia (shrimps) are common in the Antarctic. Because remoteness, depth and ice cover restrict sampling in the South Ocean, species distribution modelling is a useful tool for evaluating distributions. We used physical specimen and towed camera data to describe the diversity and distribution of shrimps in the Ross Sea region of Antarctica. Eight shrimp species were recorded: Chorismus antarcticus; Notocrangon antarcticus; Nematocarcinus lanceopes; Dendrobranchiata; Pasiphaea scotiae; Pasiphaea cf. ledoyeri; Petalidium sp., and a new species of Lebbeus. For the two most common species, N. antarcticus and N. lanceopes, we used maximum entropy modelling, based on records of 60 specimens and over 1130 observations across 23 sites in depths from 269 m to 3433 m, to predict distributions in relation to environmental variables. Two independent sets of environmental data layers at 0.05° and 0.5° resolution respectively, showed how spatial resolution affected the model. Chorismus antarcticus and N. antarcticus were found only on the continental shelf and upper slopes, while N. lanceopes, Lebbeus n. sp., Dendrobranchiata, Petalidium sp., Pasiphaea cf. ledoyeri, and Pasiphaea scotiae were found on the slopes, seamounts and abyssal plain. The environmental variables that contributed most to models for N. antarcticus were depth, chlorophyll-a concentration, temperature, and salinity, and for N. lanceopes were depth, ice concentration, seabed slope/rugosity, and temperature. The relative ranking, but not the composition of these variables changed in models using different spatial resolutions, and the predicted extent of suitable habitat was smaller in models using the finer-scale environmental layers. Our modelling indicated that shrimps were widespread throughout the Ross Sea region and were thus likely to play important functional role in the ecosystem, and that the spatial resolution of data needs to be

  14. recent changes the in flow of the Ross Ice Shelf, West Antarctica

    NASA Astrophysics Data System (ADS)

    Hulbe, C. L.; Scambos, T. A.; Bohlander, J. A.; Lee, C.

    2012-12-01

    Comparison of surface velocities measured during the Ross Ice Shelf Geophysical and Glaciological Survey (RIGGS, 1973 to 1978) and velocities measured via feature tracking between two Moderate-resolution Imaging Spectroradiometer (MODIS) mosaics (compiled from 2003-4 and 2008-9 images) reveals widespread slowing and minor areas of acceleration in the Ross Ice Shelf (RIS) over the \\~30 year interval. The largest changes (-13 m/a/a) occur near the Whillans and Mercer Ice Streams grounding line in the southernmost part of the ice shelf. Speed has increased over the interval (up to 5 m/a/a) between the MacAyeal Ice Stream grounding line and the shelf front, and along the eastern part of the shelf front. Here, a well-tested model of the ice shelf is used to discern between longer and shorter time scale transients in ice shelf flow. Changes in ice thickness computed using ICESat laser altimetry are used to test various model outcomes. The observed transients represent a combination of ongoing response to ice stream discharge variations and resulting shelf thickness changes over the past millennium and while faint impressions of past events are evident, the modern signal is dominated by shorter time scale events, including the stagnation of Kamb Ice Stream about 160 years ago, recent changes in basal drag on the Whillans Ice Stream ice plain and, apparently, iceberg calving. Details in embayment geometry, for example the shallow sea floor below Crary Ice Rise, modulate the spatial pattern of ice shelf response to flow perturbations.

  15. Bacterial abundance and composition in marine sediments beneath the Ross Ice Shelf, Antarctica.

    PubMed

    Carr, S A; Vogel, S W; Dunbar, R B; Brandes, J; Spear, J R; Levy, R; Naish, T R; Powell, R D; Wakeham, S G; Mandernack, K W

    2013-07-01

    Marine sediments of the Ross Sea, Antarctica, harbor microbial communities that play a significant role in the decomposition, mineralization, and recycling of organic carbon (OC). In this study, the cell densities within a 153-cm sediment core from the Ross Sea were estimated based on microbial phospholipid fatty acid (PLFA) concentrations and acridine orange direct cell counts. The resulting densities were as high as 1.7 × 10⁷ cells mL⁻¹ in the top ten centimeters of sediments. These densities are lower than those calculated for most near-shore sites but consistent with deep-sea locations with comparable sedimentation rates. The δ¹³C measurements of PLFAs and sedimentary and dissolved carbon sources, in combination with ribosomal RNA (SSU rRNA) gene pyrosequencing, were used to infer microbial metabolic pathways. The δ¹³C values of dissolved inorganic carbon (DIC) in porewaters ranged downcore from -2.5‰ to -3.7‰, while δ¹³C values for the corresponding sedimentary particulate OC (POC) varied from -26.2‰ to -23.1‰. The δ¹³C values of PLFAs ranged between -29‰ and -35‰ throughout the sediment core, consistent with a microbial community dominated by heterotrophs. The SSU rRNA gene pyrosequencing revealed that members of this microbial community were dominated by β-, δ-, and γ-Proteobacteria, Actinobacteria, Chloroflexi and Bacteroidetes. Among the sequenced organisms, many appear to be related to known heterotrophs that utilize OC sources such as amino acids, oligosaccharides, and lactose, consistent with our interpretation from δ¹³CPLFA analysis. Integrating phospholipids analyses with porewater chemistry, δ¹³CDIC and δ¹³CPOC values and SSU rRNA gene sequences provides a more comprehensive understanding of microbial communities and carbon cycling in marine sediments, including those of this unique ice shelf environment. PMID:23682649

  16. Controlled-source seismic investigations of the crustal structure beneath Erebus volcano and Ross Island, Antarctica: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Maraj, S.; Kyle, P. R.; Zandomeneghi, D.; Knox, H. A.; Aster, R. C.; Snelson, C. M.; Miller, P. E.; Kaip, G. M.

    2009-12-01

    During the 2008-09 Austral summer field season we undertook a controlled-source seismic experiment (Tomo-Erebus, TE) to examine the shallow magmatic system beneath the active Erebus volcano (TE-3D) and the crustal structure beneath Ross Island. Here we report on the TE-2D component, which was designed to produce a two-dimensional P-wave velocity model along an east-west profile across Ross Island. Marine geophysical observations near Ross Island have identified the north-south trending Terror Rift within the older and broader Victoria Land Basin, which are a component of the intraplate West Antarctic Rift System. Mount Erebus and Ross Island are circumstantially associated with the Terror Rift and its thin (~20 km) crust. The nature, extent and role of the Terror Rift in controlling the evolution of Ross Island volcanism and the on-going eruptive activity of Erebus volcano are unknown. In TE-2D, we deployed 21 seismic recorders (Ref Tek 130) with three-component 4.5 Hz geophones (Sercel L-28-3D) along a 90-km east-west line between Capes Royds and Crozier. These were supplemented by 79 similar instruments deployed for the high-resolution TE-3D experiment within a 3 x 3 km grid around the summit crater of Erebus, an array of 8 permanent short period and broadband sensors used to monitor the activity of Erebus and 23 three-component sensors (Guralp CMG-40T, 30s-100 Hz) positioned around the flanks and summit of Erebus. Fifteen chemical sources were loaded in holes drilled about 15 m deep in the snow and ice. The size of these shots ranged from 75 to 600 kg of ANFO with the largest shots at the ends of the profile. An additional shot was detonated in the sea (McMurdo Sound) using 200 kg of dynamite. Due to the rugged terrain, short field seasons and large area to be covered, the seismometer spacing along the TE-2D profile is quite large (~ 5 km spacing), resulting in poor near-surface data resolution. However, the data have a high signal to noise ratio with clear

  17. "All this that has happened to me shouldn't happen to nobody else": Loretta Ross and the Women of Color Reproductive Freedom Movement of the 1980s.

    PubMed

    Nelson, Jennifer

    2010-01-01

    Loretta Ross exemplifies women of color feminist participation in and transformation of the women's health movement of the 1970s and 1980s. Ross helped build a women's health movement that by the late 1980s made the demands of women of color central. This movement was attractive to many women of color who had rejected the collapse of a broader women's health movement into the abortion rights movement as too narrowly focused. Many women of color activists, including Ross, argued that the emphasis on abortion rights and choice failed to address the linked socioeconomic and community health issues confronted by many women of color and poor women. Ross's work spurred coalition building among white women and women of color that focused on expanding reproductive justice and women's health beyond legal abortion. By the 1990s these efforts had produced a vibrant and engaged feminist reproductive justice movement that promoted the socioeconomics of good health for all women. PMID:20857595

  18. Holocene climate variability from ice core records in the Ross Sea area (East Antarctica)

    NASA Astrophysics Data System (ADS)

    Braida, Martina; Stenni, Barbara; Masson-Delmotte, Valerie; Pol, Katy; Selmo, Enricomaria; Mezgec, Karin

    2014-05-01

    Past polar climate variability can be documented at high resolution thanks to ice core records, which have revealed significant Holocene variations in Antarctica. Paleotemperature reconstructions from Antarctic ice cores are mainly based on δ18O (δD) records, a proxy for local, precipitation-weighted atmospheric temperatures. Here, we present a new climate record spanning the past 12,000 years resulting from high resolution (10 cm) stable isotope analyses of the ice core drilled at Talos Dome (TD) in East Antarctica from 2003 to 2007 in the framework of the TALDICE (TALos Dome Ice CorE) project. Talos Dome (72°49'S, 159°11'E; 2315 m; -41°C) is an ice dome on the edge of the East Antarctic plateau, where moisture is mainly advected from the Indian and western Pacific sectors of the Southern Ocean. Pacific moisture arriving at TD has been transported above the Ross Sea, where extensive presence of sea ice also occurs during summer. High-resolution δ18O data have been measured using both IRMS and CRDS techniques on 10 cm samples, leading to a mean time resolution of two years. The long-term trend of the TALDICE δ18O profile shows characteristic features already observed in other ice cores from the East Antarctic plateau. Following the approach of Pol et al. (2011), high frequency climate variability has been investigated using a 3000-year running standard deviation on the de-trended record. The results are compared to the same analysis performed on the nearby Taylor Dome ice core δ18O data, which is the single East Antarctic ice core showing a strong Holocene decreasing trend. Despite these trend differences, both sites share common features regarding changes in variance. We also investigate changes in deuterium excess, a proxy reflecting changes in moisture source conditions. Both deuterium excess records show a two-step increasing trend in the first part of the Holocene. Taylor Dome deuterium excess however depicts an enhanced variability since about 7000

  19. Unravelling textural heterogeneity in obsidian: Shear-induced outgassing in the Rocche Rosse flow

    NASA Astrophysics Data System (ADS)

    Shields, J. K.; Mader, H. M.; Caricchi, L.; Tuffen, H.; Mueller, S.; Pistone, M.; Baumgartner, L.

    2016-01-01

    Obsidian flow emplacement is a complex and understudied aspect of silicic volcanism. Of particular importance is the question of how highly viscous magma can lose sufficient gas in order to erupt effusively as a lava flow. Using an array of methods we study the extreme textural heterogeneity of the Rocche Rosse obsidian flow in Lipari, a 2 km long, 100 m thick, ~ 800 year old lava flow, with respect to outgassing and emplacement mechanisms. 2D and 3D vesicle analyses and density measurements are used to classify the lava into four textural types: 'glassy' obsidian (< 15% vesicles), 'pumiceous' lava (> 40% vesicles), high aspect ratio, 'shear banded' lava (20-40% vesicles) and low aspect ratio, 'frothy' obsidian with 30-60% vesicles. Textural heterogeneity is observed on all scales (m to μm) and occurs as the result of strongly localised strain. Magnetic fabric, described by oblate and prolate susceptibility ellipsoids, records high and variable degrees of shearing throughout the flow. Total water contents are derived using both thermogravimetry and infrared spectroscopy to quantify primary (magmatic) and secondary (meteoric) water. Glass water contents are between 0.08-0.25 wt.%. Water analysis also reveals an increase in water content from glassy obsidian bands towards 'frothy' bands of 0.06-0.08 wt.%, reflecting preferential vesiculation of higher water bands and an extreme sensitivity of obsidian degassing to water content. We present an outgassing model that reconciles textural, volatile and magnetic data to indicate that obsidian is generated from multiple shear-induced outgassing cycles, whereby vesicular magma outgasses and densifies through bubble collapse and fracture healing to form obsidian, which then re-vesiculates to produce 'dry' vesicular magma. Repetition of this cycle throughout magma ascent results in the low water contents of the Rocche Rosse lavas and the final stage in the degassing cycle determines final lava porosity. Heterogeneities in

  20. Velocity Structure of the Rifted Crust in the Northwestern Ross Sea, From Seismic Refraction Data

    NASA Astrophysics Data System (ADS)

    Selvans, M. M.; Stock, J. M.; Clayton, R. W.; Cande, S. C.; Davey, F. J.

    2007-12-01

    Extension in the West Antarctic Rift System produced the Transantarctic Mountains, deep sedimentary basins in the Ross Sea, and the Adare Trough spreading center (43 to 26 Ma). The Adare Basin and Northern Basin are located at the northwesternmost extent of this region of deformation, and are generally assumed to be oceanic and continental crust respectively. Their boundary therefore provides an ideal study area for linking the styles of extension in the two types of crust. We process seismic refraction data collected during research cruise NBP0701 to determine 2D crustal velocity models along four seismic lines at the margin of the Adare and Northern Basins. The 48 closely-spaced sonobuoy records included in this study provide continuous refraction data coverage; three of these lines have reversed sonobuoy records. Finite difference modeling of the individual sonobuoys provides accuracy in our interpreted layer velocities, confidence in tracing refracted arrivals back to their associated reflections in the sonobuoy records, and the ability to match these reflected arrivals with the multi- channel seismic reflection data. Preliminary results from the line trending perpendicular to the margin of the Adare and Northern Basins show no change in crustal velocity structure from one basin to the other, with nearly flat velocity contours along the entire line. An apparent velocity of 8000 m/s is observed along this line in the Northern Basin. A comparable layer velocity is not detected in the sonobuoy record shot in the reverse direction, so this velocity could be due to local basement topography. Alternatively, the high velocity may indicate mantle material, and an unusually thin crust at that location. We model structural layers and associated velocities below the sea floor in order to better understand the physical structure and deformational history of the crust in the northwestern Ross Sea. The velocity horizons determined from this data set provide model constraints

  1. Velocity Structure of the Rifted Crust in the Northwestern Ross Sea, From Seismic Refraction Data

    NASA Astrophysics Data System (ADS)

    Selvans, M. M.; Stock, J. M.; Clayton, R. W.; Cande, S. C.; Davey, F. J.

    2004-12-01

    Extension in the West Antarctic Rift System produced the Transantarctic Mountains, deep sedimentary basins in the Ross Sea, and the Adare Trough spreading center (43 to 26 Ma). The Adare Basin and Northern Basin are located at the northwesternmost extent of this region of deformation, and are generally assumed to be oceanic and continental crust respectively. Their boundary therefore provides an ideal study area for linking the styles of extension in the two types of crust. We process seismic refraction data collected during research cruise NBP0701 to determine 2D crustal velocity models along four seismic lines at the margin of the Adare and Northern Basins. The 48 closely-spaced sonobuoy records included in this study provide continuous refraction data coverage; three of these lines have reversed sonobuoy records. Finite difference modeling of the individual sonobuoys provides accuracy in our interpreted layer velocities, confidence in tracing refracted arrivals back to their associated reflections in the sonobuoy records, and the ability to match these reflected arrivals with the multi- channel seismic reflection data. Preliminary results from the line trending perpendicular to the margin of the Adare and Northern Basins show no change in crustal velocity structure from one basin to the other, with nearly flat velocity contours along the entire line. An apparent velocity of 8000 m/s is observed along this line in the Northern Basin. A comparable layer velocity is not detected in the sonobuoy record shot in the reverse direction, so this velocity could be due to local basement topography. Alternatively, the high velocity may indicate mantle material, and an unusually thin crust at that location. We model structural layers and associated velocities below the sea floor in order to better understand the physical structure and deformational history of the crust in the northwestern Ross Sea. The velocity horizons determined from this data set provide model constraints

  2. Using melt inclusions to track the evolution of primitive alkalic magmas from Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Rasmussen, D. J.; Kyle, P. R.; Wallace, P. J.

    2013-12-01

    Melt inclusions (MI) provide a means for measuring the dissolved volatile (H2O, CO2, S, Cl, F), major and trace element compositions of magmas at depth. Such data are valuable for assessing the physical and chemical conditions within a magmatic system by providing snapshots of magma compositions during ascent and evolution. Here we examine MI in 9 samples of rapidly quenched basanitic ash and hyaloclastite from three locations (Hut Point, Mt. Terror, Mt. Bird) on Ross Island, Antarctica, which radially surround the active, phonolitic Erebus volcano. Ross Island is an intraplate volcanic center located at the southern end of the Terror Rift, an area of active continental extension. Geophysical data show that below the 19-27 km thick crust is a localized region of anomalously hot upwelling mantle. We analyzed volatiles and major elements in 93 olivine-hosted (Fo 78.2-88.3) MI using FTIR spectroscopy and electron microprobe analysis, and all compositions were corrected for the effects of post-entrapment olivine crystallization. Preliminary results show the MI have a range of basanite compositions (SiO2 39.1-45.2 wt.%; Mg# 50.1-66.5). The MI major element trends further suggest the 9 samples are genetically related and may have a common low degree partial melt parental magma. CO2 contents range from ~0.1 to 0.85 wt.%, which are amongst the highest ever measured in MI. H2O contents are ~1 to 1.9 wt.%. The MI also have high concentrations of S, Cl, and F with maximum values of 0.27, 0.22, and 0.14 wt.%, respectively. The H2O and CO2 concentrations require entrapment pressures between ~250 and 600 MPa. Thus, the MI record a magmatic history that begins at near-Moho depths and is exceptionally CO2-rich. Because of its low solubility in magmas CO2 must be the major volatile driving the eruption of these alkalic magmas. More evolved Erebus MI (SiO2 43.4-53.6 wt.%; Mg# 32.9-55.1) from an earlier study [1] have consistently lower H2O concentrations. [1] Oppenheimer et al

  3. A New Analysis of the Two Classical ZZ Ceti White Dwarfs GD 165 and Ross 548. I. Photometry and Spectroscopy

    NASA Astrophysics Data System (ADS)

    Giammichele, N.; Fontaine, G.; Bergeron, P.; Brassard, P.; Charpinet, S.; Pfeiffer, B.; Vauclair, G.

    2015-12-01

    We present the first of a two-part seismic analysis of the two bright hot ZZ Ceti stars GD 165 and Ross 548. In this first part, we report the results of frequency extraction exercises based on time-series data sets of exceptional quality. We uncovered up to 13 independent pulsation modes in GD 165, regrouped into six main frequency multiplets. These include 9 secure (signal-to-noise ratio, S/N > 4) detections and 4 possible ones (4 ≥ S/N ≥ 3). Likewise, we isolated 11 independent modes in Ross 548 (9 secure and 2 possible detections), also regrouped into 6 multiplets. The multiplet structure is likely caused by rotational splitting. We also provide updated estimates of the time-averaged atmospheric properties of these two pulsators in the light of recent developments on the front of atmospheric modeling for DA white dwarfs.

  4. Twentieth century sea-ice trends in the Ross Sea from a high-resolution, coastal ice-core record

    NASA Astrophysics Data System (ADS)

    Sinclair, Kate E.; Bertler, Nancy A. N.; Bowen, Melissa M.; Arrigo, Kevin R.

    2014-05-01

    We present the first proxy record of sea-ice area (SIA) in the Ross Sea, Antarctica, from a 130 year coastal ice-core record. High-resolution deuterium excess data show prevailing stable SIA from the 1880s until the 1950s, a 2-5% reduction from the mid-1950s to the early-1990s, and a 5% increase after 1993. Additional support for this reconstruction is derived from ice-core methanesulphonic acid concentrations and whaling records. While SIA has continued to decline around much of the West Antarctic coastline since the 1950s, concurrent with increasing air and ocean temperatures, the underlying trend is masked in the Ross Sea by a switch to positive SIA anomalies since the early-1990s. This increase is associated with a strengthening of southerly winds and the enhanced northward advection of sea ice.

  5. The Origin of a Layer of Subcircular Mudflakes in the Ross Sandstone Formation of County Clare, Ireland

    NASA Astrophysics Data System (ADS)

    Robinson, K. H.; Kackstaetter, U. R.

    2015-12-01

    The west coast of Ireland in County Clare is famous for its Paleozoic stratigraphy containing spectacular exposures of deposits from carbonate shelf, deep marine, slope and deltaic environments, exposed at several distinctive and well-known locations including the Burren, Cliffs of Moher, and Bridges of Ross. Underlying the silty sandstones of the Gull Island Formation and overlying the Clare Shale, the Carboniferous Ross Sandstone Formation comprises a series of fine-grained sandstone and mudstone deep water turbidite deposits. Approximately a half-kilometer northeast of the Bridges of Ross and about 15 meters below the upper boundary of the Ross Formation is a particular stratum exhibiting an assemblage of unique circular to ovoid impressions. These features densely cover an exposed horizontal surface of approximately 100 square meters, positioned about 5 meters above and adjacent to a cluster of sand volcanoes. The impressions frequently overlap and completely cover the exposed surface of the rock unit and continue along the same plane of the buried portion of the stratum. Diameters of the impressions range between 2 and 20 centimeters, and many contain clasts of pale grey shale or claystone material. Samples were collected from the layer of interest as well as from subjacent and superjacent strata, spanning a total thickness of just over 1 meter. Thin sections were created and analyzed to determine both composition and estimated porosity of the rock in a continuous vertical cross-section through the series of strata surrounding the impressions. Characteristics of each stratum were examined to explore possible depositional relationships of each layer to the others and to indicate likely diagenetic processes of the subcircular features. Two broad possible origins are discussed: a primary sedimentary origin, i.e. turbidite channel mudflake conglomerate; or a post-depositional soft sediment deformation origin due to either (i) sediment loading and dewatering, (ii

  6. Serum chemistry and antibodies against pathogens in antarctic fur seals, Weddell seals, crabeater seals, and Ross seals.

    PubMed

    Tryland, Morten; Nymo, Ingebjørg H; Nielsen, Ole; Nordøy, Erling S; Kovacs, Kit M; Krafft, Bjørn A; Thoresen, Stein I; Åsbakk, Kjetil; Osterrieder, Klaus; Roth, Swaantje J; Lydersen, Christian; Godfroid, Jacques; Blix, Arnoldus S

    2012-07-01

    Information on health parameters, such as antibody prevalences and serum chemistry that can reveal exposure to pathogens, disease, and abnormal physiologic conditions, is scarce for Antarctic seal species. Serum samples from Antarctic fur seals (Arctocephalus gazella, n=88) from Bouvetøya (2000-2001 and 2001-2002), and from Weddell seals (Leptonychotes weddellii, n=20), Ross seals (Ommatophoca rossii, n=20), and crabeater seals (Lobodon carcinophagus, n=9) from the pack-ice off Queen Maud Land, Antarctica (2001) were analyzed for enzyme activity, and concentrations of protein, metabolites, minerals, and cortisol. Adult Antarctic fur seal males had elevated levels of total protein (range 64-99 g/l) compared to adult females and pups (range 52-79 g/l). Antarctic fur seals had higher enzyme activities of creatine kinase, lactate dehydrogenase, and amylase, compared to Weddell, Ross, and crabeater seals. Antibodies against Brucella spp. were detected in Weddell seals (37%), Ross seals (5%), and crabeater seals (11%), but not in Antarctic fur seals. Antibodies against phocine herpesvirus 1 were detected in all species examined (Antarctic fur seals, 58%; Weddell seals, 100%; Ross seals, 15%; and crabeater seals, 44%). No antibodies against Trichinella spp., Toxoplasma, or phocine distemper virus (PDV) were detected (Antarctic fur seals were not tested for PDV antibodies). Antarctic seals are challenged by reduced sea ice and increasing temperatures due to climate change, and increased anthropogenic activity can introduce new pathogens to these vulnerable ecosystems and represent a threat for these animals. Our data provide a baseline for future monitoring of health parameters of these Antarctic seal species, for tracking the impact of environmental, climatic, and anthropogenic changes in Antarctica over time. PMID:22740529

  7. An optimized estimate of glacial melt from the Ross Ice Shelf using noble gases, stable isotopes, and CFC transient tracers

    NASA Astrophysics Data System (ADS)

    Loose, B.; Schlosser, P.; Smethie, W. M.; Jacobs, S.

    2009-08-01

    Isotopes of helium and neon and the H218O/H216O ratio of water are proven proxies for melt from glacial ice beneath floating ice shelves and at ice shelf fronts. Their high concentrations in glacial meltwater, compared to other environmental sources, make them ideal tracers for studies of the pathways of glacial meltwater from its origins into the ocean interior. We combine noble gas and stable isotopes with temperature, salinity, and dissolved oxygen measurements from three cruises (along the Ross Ice Shelf during the austral summers of 1993-1994 and 1999-2000 and to the Ross Sea in 2000-2001) and use optimal multiparameter analysis to compute the water mass concentration, including glacial meltwater. The distribution of meltwater at the front of the Ross Ice Shelf extended east from 180°W, with the highest concentrations found near 165°W in both 1994 and 2000. The mean meltwater concentration at the ice shelf front was 2.0 ± 0.33‰ in 1994, 2.2 ± 0.36‰ in 2000, and 0.25 ± 0.1‰ in the western Ross Sea in 2001. Water mass concentrations are used to correct for bias in the CFC age, introduced by mixing with CFC-free waters, an effect revealed by comparing CFC age with transit time distribution curves. The water residence time within the ice shelf cavity, using CFCs and the mean meltwater concentration, implies a basal melt rate of 33-50 km3 a-1.

  8. Volcano-ice-sea interaction in the Cerro Santa Marta area, northwest James Ross Island, Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Calabozo, Fernando M.; Strelin, Jorge A.; Orihashi, Yuji; Sumino, Hirochika; Keller, Randall A.

    2015-05-01

    We present here the results of detailed mapping, lithofacies analysis and stratigraphy of the Neogene James Ross Island Volcanic Group (Antarctic Peninsula) in the Cerro Santa Marta area (northwest of James Ross Island), in order to give constraints on the evolution of a glaciated volcanic island. Our field results included recognition and interpretation of seventeen volcanic and glacial lithofacies, together with their vertical and lateral arrangements, supported by four new unspiked K-Ar ages. This allowed us to conclude that the construction of the volcanic pile in this area took place during two main eruptive stages (Eruptive Stages 1 and 2), separated from the Cretaceous bedrock and from each other by two major glacial unconformities (U1 and U2). The U1 unconformity is related to Antarctic Peninsula Ice sheet expansion during the late Miocene (before 6.2 Ma) and deposition of glacial lithofacies in a glaciomarine setting. Following this glacial advance, Eruptive Stage 1 (6.2-4.6 Ma) volcanism started with subaerial extrusion of lava flows from an unrecognized vent north of the study area, with eruptions later fed from vent/s centered at Cerro Santa Marta volcano, where cinder cone deposits and a volcanic conduit/lava lake are preserved. These lava flows fed an extensive (> 7 km long) hyaloclastite delta system that was probably emplaced in a shallow marine environment. A second unconformity (U2) was related to expansion of a local ice cap, centered on James Ross Island, which truncated all the eruptive units of Eruptive Stage 1. Concomitant with glacier advance, renewed volcanic activity (Eruptive Stage 2) started after 4.6 Ma and volcanic products were fed again by Cerro Santa Marta vents. We infer that glaciovolcanic eruptions occurred under a moderately thin (~ 300 m) glacier, in good agreement with previous estimates of paleo-ice thickness for the James Ross Island area during the Pliocene.

  9. Carbonate saturation state of surface waters in the Ross Sea and Southern Ocean: controls and implications for the onset of aragonite undersaturation

    NASA Astrophysics Data System (ADS)

    DeJong, H. B.; Dunbar, R. B.; Mucciarone, D.; Koweek, D. A.

    2015-12-01

    Predicting when surface waters of the Ross Sea and Southern Ocean will become undersaturated with respect to biogenic carbonate minerals is challenging in part due to the lack of baseline high-resolution carbon system data. Here we present ~ 1700 surface total alkalinity measurements from the Ross Sea and along a transect between the Ross Sea and southern Chile from the austral autumn (February-March 2013). We calculate the saturation state of aragonite (ΩAr) and calcite (Ω Ca) using measured total alkalinity and pCO2. In the Ross Sea and south of the Polar Front, variability in carbonate saturation state (Ω) is mainly driven by algal photosynthesis. Freshwater dilution and calcification have minimal influence on Ω variability. We estimate an early spring surface water ΩAr value of ~ 1.2 for the Ross Sea using a total alkalinity-salinity relationship and historical pCO2 measurements. Our results suggest that the Ross Sea is not likely to become undersaturated with respect to aragonite until the year 2070.

  10. Iron Fertilization of the Southern Ocean: Regional Simulation and Analysis of C-Sequestration in the Ross Sea

    SciTech Connect

    Kevin Arrigo

    2012-03-13

    A modified version of the dynamic 3-dimensional mesoscale Coupled Ice, Atmosphere, and Ocean model (CIAO) of the Ross Sea ecosystem has been used to simulate the impact of environmental perturbations upon primary production and biogenic CO2 uptake. The Ross Sea supports two taxonomically, and spatially distinct phytoplankton populations; the haptophyte Phaeocystis antarctica and diatoms. Nutrient utilization ratios predict that P. antarctica and diatoms will be driven to nitrate and phosphate limitation, respectively. Model and field data have confirmed that the Ross Sea is iron limited with only two-thirds of the macronutrients consumed by the phytoplankton by the end of the growing season. In this study, the CIAO model was improved to simulate a third macronutrient (phosphate), dissolved organic carbon, air-sea gas exchange, and the carbonate system. This enabled us to effectively model pCO2 and subsequently oceanic CO2 uptake via gas exchange, allowing investigations into the affect of alleviating iron limitation on both pCO2 and nutrient drawdown.

  11. 40Ar-39Ar Age Constraints on Volcanism and Tectonism in the Terror Rift of the Ross Sea, Antarctica

    USGS Publications Warehouse

    2007-01-01

    Volcanic sills and dikes inferred from seismic reflection profiles and geophysical studies of the Ross Sea are thought to be related to the rift basins in the region, and their emplacement to be coeval with extension. However, lack of precise geochronology in the Terror Rift of the Ross Sea region has left these inferred relationships poorly constrained and has hindered neotectonic studies, because of the large temporal gaps between seismic reflectors of known ages. New 40Ar/39Ar geochronology presented here for submarine volcanic rocks provides better age constraints for neotectonic interpretations within the Terror Rift. Several samples from seamounts yielded young ages between 156 ± 21 and 122 ± 26 Ka. These ages support interpretations that extension within the Terror Rift was active at least through the Pleistocene. Three evenly spaced samples from the lowermost 100 m of Franklin Island range in age from 3.28 ± 0.04 to 3.73 ± 0.05 Ma. These age determinations demonstrate that construction of a small volcanic edifice such as Franklin Island took at least several hundred thousand years, and therefore that much larger ones in the Erebus Volcanic Province are likely to have taken considerably longer than previously inferred. This warrants caution in applying a limited number of age determinations to define the absolute ages of events in the Ross Sea region

  12. Eco-environmental implications of elemental and carbon isotope distributions in ornithogenic sediments from the Ross Sea region, Antarctica

    NASA Astrophysics Data System (ADS)

    Liu, Xiaodong; Nie, Yaguang; Sun, Liguang; Emslie, Steven D.

    2013-09-01

    Seabirds have substantial influence on geochemical circulation of elements, serving as a link for substance exchange between their foraging area and colonies. In this study, we investigated the elemental and carbon isotopic composition of five penguin-affected sediment profiles excavated from Ross Island and Beaufort Island in the Ross Sea region, Antarctica. Among the three main constituents of the sediments (including weathered bedrock, guano and algae), guano was the main source of organic matter and nutrients, causing selective enrichment of several elements in each of the sediment profiles. In the 22 measured elements, As, Cd, Cu, P, S, Se and Zn were identified as penguin bio-elements in the Ross Sea region through statistical analysis and comparison with local end-member environmental media such as weathered bedrock, fresh guano and fresh algae. Carbon isotopic composition in the ornithogenic sediments showed a mixing feature of guano and algae. Using a two-member isotope mixing equation, we were able to reconstruct the historical change of guano input and algal bio-mass. Compared with research in other parts of Antarctic, Arctic, and South China Sea, we found apparent overlap of avian bio-elements including As, Cd, Cu, P, Se, and Zn. Information on the composition and behavior of bio-elements in seabird guano on a global scale, and the role that bio-vectors play in the geochemical circulation between land and sea, will facilitate future research on avian ecology and paleoclimatic reconstruction.

  13. From warm to cold: migration of Adélie penguins within Cape Bird, Ross Island

    NASA Astrophysics Data System (ADS)

    Nie, Yaguang; Sun, Liguang; Liu, Xiaodong; Emslie, Steven D.

    2015-06-01

    Due to their sensitivity to environmental change, penguins in Antarctica are widely used as bio-indicators in paleoclimatic research. On the basis of bio-element assemblages identified in four ornithogenic sediment profiles, we reconstructed the historical penguin population change at Cape Bird, Ross Island, for the past 1600 years. Clear succession of penguin population peaks were observed in different profiles at about 1400 AD, which suggested a high probability of migration within this region. The succession was most obviously marked by a sand layer lasting from 1400 to 1900 AD in one of the analyzed profiles. Multiple physical/chemical parameters indicated this sand layer was not formed in a lacustrine environment, but was marine-derived. Both isostatic subsidence and frequent storms under the colder climatic condition of the Little Ice Age were presumed to have caused the abandonment of the colonies, and we believe the penguins migrated from the coastal area of mid Cape Bird northward and to higher ground as recorded in the other sediment profiles. This migration was an ecological response to global climate change and possible subsequent geological effects in Antarctica.

  14. Unusual biogenic calcite structures in two shallow lakes, James Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Elster, J.; Nedbalová, L.; Vodrážka, R.; Láska, K.; Haloda, J.; Komárek, J.

    2016-01-01

    The floors of two shallow endorheic lakes, located on volcanic surfaces on James Ross Island, are covered with calcareous organosedimentary structures. Their biological and chemical composition, lake water characteristics, and seasonal variability of the thermal regime are introduced. The lakes are frozen down to the bottom for 8-9 months a year and their water chemistry is characterised by low conductivity and neutral to slightly alkaline pH. The photosynthetic microbial mat is composed of filamentous cyanobacteria and microalgae that are considered to be Antarctic endemic species. The mucilaginous black biofilm is covered by green spots formed by a green microalga and the macroscopic structures are packed together with fine material. Thin sections consist of rock substrate, soft biofilm, calcite spicules and mineral grains originating from different sources. The morphology of the spicules is typical of calcium carbonate monocrystals having a layered structure and specific surface texture, which reflect growth and degradation processes. The spicules' chemical composition and structure correspond to pure calcite. The lakes' age, altitude, morphometry, geomorphological and hydrological stability, including low sedimentation rates, together with thermal regime predispose the existence of this community. We hypothesise that the precipitation of calcite is connected with the photosynthetic activity of the green microalgae that were not recorded in any other lake in the region. This study has shown that the unique community producing biogenic calcite spicules is quite different to any yet described.

  15. Antimicrobial Activity of Monoramnholipids Produced by Bacterial Strains Isolated from the Ross Sea (Antarctica).

    PubMed

    Tedesco, Pietro; Maida, Isabel; Palma Esposito, Fortunato; Tortorella, Emiliana; Subko, Karolina; Ezeofor, Chidinma Christiana; Zhang, Ying; Tabudravu, Jioji; Jaspars, Marcel; Fani, Renato; de Pascale, Donatella

    2016-05-01

    Microorganisms living in extreme environments represent a huge reservoir of novel antimicrobial compounds and possibly of novel chemical families. Antarctica is one of the most extraordinary places on Earth and exhibits many distinctive features. Antarctic microorganisms are well known producers of valuable secondary metabolites. Specifically, several Antarctic strains have been reported to inhibit opportunistic human pathogens strains belonging to Burkholderia cepacia complex (Bcc). Herein, we applied a biodiscovery pipeline for the identification of anti-Bcc compounds. Antarctic sub-sea sediments were collected from the Ross Sea, and used to isolate 25 microorganisms, which were phylogenetically affiliated to three bacterial genera (Psychrobacter, Arthrobacter, and Pseudomonas) via sequencing and analysis of 16S rRNA genes. They were then subjected to a primary cell-based screening to determine their bioactivity against Bcc strains. Positive isolates were used to produce crude extracts from microbial spent culture media, to perform the secondary screening. Strain Pseudomonas BNT1 was then selected for bioassay-guided purification employing SPE and HPLC. Finally, LC-MS and NMR structurally resolved the purified bioactive compounds. With this strategy, we achieved the isolation of three rhamnolipids, two of which were new, endowed with high (MIC < 1 μg/mL) and unreported antimicrobial activity against Bcc strains. PMID:27128927

  16. Mapping the grounding zone of Ross Ice Shelf using ICESat laser altimetry

    USGS Publications Warehouse

    Brunt, Kelly M.; Fricker, Helen A.; Padman, Laurie; Scambos, Ted A.; O'Neel, Shad

    2010-01-01

    We use laser altimetry from the Ice, Cloud, and land Elevation Satellite (ICESat) to map the grounding zone (GZ) of the Ross Ice Shelf, Antarctica, at 491 locations where ICESat tracks cross the grounding line (GL). Ice flexure in the GZ occurs as the ice shelf responds to short-term sea-level changes due primarily to tides. ICESat repeat-track analysis can be used to detect this region of flexure since each repeated pass is acquired at a different tidal phase; the technique provides estimates for both the landward limit of flexure and the point where the ice becomes hydrostatically balanced. We find that the ICESat-derived landward limits of tidal flexure are, in many places, offset by several km (and up to ∼60 km) from the GL mapped previously using other satellite methods. We discuss the reasons why different mapping methods lead to different GL estimates, including: instrument limitations; variability in the surface topographic structure of the GZ; and the presence of ice plains. We conclude that reliable and accurate mapping of the GL is most likely to be achieved when based on synthesis of several satellite datasets

  17. Characteristics of the near-surface atmosphere over the Ross Ice Shelf, Antarctica

    NASA Astrophysics Data System (ADS)

    Cassano, John J.; Nigro, Melissa A.; Lazzara, Matthew A.

    2016-04-01

    Two years of data from a 30 m instrumented tower are used to characterize the near-surface atmospheric state over the Ross Ice Shelf, Antarctica. Stable stratification dominates the surface layer at this site, occurring 83% of the time. The strongest inversions occur for wind speeds less than 4 m s-1 and the inversion strength decreases rapidly as wind speed increases above 4 m s-1. In summer unstable stratification occurs 50% of the time and unstable conditions are observed in every season. A novel aspect of this work is the use of an artificial neural network pattern identification technique, known as self-organizing maps, to objectively identify characteristic potential temperature profiles that span the range of profiles present in the 2 year study period. The self-organizing map clustering technique allows the more than 100,000 observed potential temperature profiles to be represented by just 30 patterns. The pattern-averaged winds show distinct and physically consistent relationships with the potential temperature profiles. The strongest winds occur for the nearly well mixed but slightly stable patterns and the weakest winds occur for the strongest inversion patterns. The weakest wind shear over the depth of the tower occurs for slightly unstable profiles and the largest wind shear occurs for moderately strong inversions. Pattern-averaged log wind profiles are consistent with theoretical expectations. The log wind profiles exhibit a kinked profile for the strongest inversion cases indicative of decoupling of the winds between the bottom and top of the tower.

  18. Description of Pseudomonas gregormendelii sp. nov., a Novel Psychrotrophic Bacterium from James Ross Island, Antarctica.

    PubMed

    Kosina, Marcel; Švec, Pavel; Černohlávková, Jitka; Barták, Miloš; Snopková, Kateřina; De Vos, Paul; Sedláček, Ivo

    2016-07-01

    During the microbiological research performed within the scope of activities of Czech expeditions based at the Johann Gregor Mendel Station at James Ross Island, Antarctica, two psychrotrophic gram-stain negative non-fluorescent strains CCM 8506T and CCM 8507 from soil were extensively characterized using genotypic and phenotypic methods. Initial characterization using ribotyping with HindIII restriction endonuclease and phenotyping implies that both isolates belong to a single Pseudomonas species. Sequencing of rrs, rpoB, rpoD and glnA genes of strain CCM 8506(T) confirmed affiliation of investigated strains within the genus Pseudomonas. Further investigation using automated ribotyping with EcoRI (RiboPrinter(®) Microbial Characterisation System), whole-cell protein profiling using the Agilent 2100 Bioanalyzer system, extensive biochemical testing and DNA-DNA hybridization experiments confirmed that both investigated strains are members of a single taxon which is clearly separated from all hitherto described Pseudomonas spp. Based on all findings, we describe a novel species Pseudomonas gregormendelii sp. nov. with the type strain CCM 8506(T) (=LMG 28632T). PMID:27032403

  19. Monitoring and identification of airborne fungi at historic locations on Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Duncan, Shona M.; Farrell, Roberta L.; Jordan, Neville; Jurgens, Joel A.; Blanchette, Robert A.

    2010-08-01

    Air sampling in the ‘Heroic Era’ historic huts on Ross Island, Antarctica confirmed fungal presence, viability and winter survival. Cultivation and consensus sequence-based identification of Cladosporium cladosporioides, Pseudeurotium desertorum, Geomyces sp. and Antarctomyces psychrotrophicus demonstrated that they dominated the air environment within the huts. Cadophora sp. and Thebolus sp. were also isolated from the air and identified by morphological characteristics. Viable fungal colony forming units generally dropped in winter 2007 samplings from levels recorded in summer 2006 but were still substantial and greater than observed in summer 2008 and summer 2009 sampling at some locations. Comparing interior to exterior sampling, at the Hut Point and Cape Evans sites, there were more fungi recovered from the air in the interiors but at Cape Royds location, more fungi were recovered from the outside environment, possibly due to the impact of large amounts of organic material from the nearby Adélie penguin rookery. This research reveals airborne fungal biodiversity in summer and winter and demonstrates spores are widespread particularly in the interiors of the huts. Completed conservation efforts appear to have reduced fungal blooms and spores, which should reduce future adverse impacts to wood, textiles, paper and other artefacts so that this important polar heritage can be preserved.

  20. Dynamics and GPR stratigraphy of a polar rock glacier on James Ross Island, Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Fukui, Kotaro; Sone, Toshio; Strelin, Jorge A.; Torielli, Cesar A.; Mori, Junko; Fujii, Yoshiyuki

    We describe field measurements (ground-penetrating radar (GPR), geodetic survey and ice-core drilling) to provide new information on the movement mechanism and internal structure of a polar rock glacier on James Ross Island, Antarctic Peninsula. We collected GPR data along longitudinal and transverse profiles. The longitudinal GPR profiles identify inter-bedded debris-rich layers that dip up-glacier, similar to the thrust structures in the compression zone of a valley glacier. The transverse GPR profiles indicate a syncline structure inclined towards the central part of the rock glacier, resembling the transverse foliation of a valley glacier. The stratigraphy of two boreholes shows that the rock glacier consists primarily of bubbly ice with thin debris-rich layers, an internal structure similar to the `nested spoons' structure common in the interior of valley glaciers. These results indicate that the glacier motion is controlled by shear movement, common in valley glaciers. The geodetic survey confirms that flow velocities decrease towards the lower part of the rock glacier. Such heterogeneous movement causes longitudinal compression and forms thrusts which then create the debris-rich layer by uplifting basal ice and debris. Pushing of the upstream ice against the downstream ice bends the surface layers, forming transverse ridges on the rock glacier surface.

  1. Deep crustal structure of the Adare and Northern Basins, Ross Sea, Antarctica, from sonobuoy data

    NASA Astrophysics Data System (ADS)

    Selvans, M. M.; Stock, J. M.; Clayton, R. W.; Cande, S.; Granot, R.

    2014-11-01

    Extension associated with ultraslow seafloor spreading within the Adare Basin, in oceanic crust just north of the continental shelf in the Ross Sea, Antarctica, extended south into the Northern Basin. Magnetic and gravity anomaly data suggest continuity of crustal structure across the continental shelf break that separates the Adare and Northern Basins. We use sonobuoy refraction data and multi-channel seismic (MCS) reflection data collected during research cruise NBP0701, including 71 new sonobuoy records, to provide constraints on crustal structure in the Adare and Northern Basins. Adjacent 1D sonobuoy profiles along several MCS lines reveal deep crustal structure in the vicinity of the continental shelf break, and agree with additional sonobuoy data that document fast crustal velocities (6000-8000 m/s) at shallow depths (1-6 km below sea level) from the Adare Basin to the continental shelf, a structure consistent with that of other ultraslow-spread crust. Our determination of crustal structure in the Northern Basin only extends through sedimentary rock to the basement rock, and so cannot help to distinguish between different hypotheses for formation of the basin.

  2. Ambient Seismic Noise Correlation on Iceberg C16, Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Okal, E. A.; MacAyeal, D. R.

    2014-12-01

    This study focuses on the ambient noise transmission between 4 seismometer stations distributed on iceberg C16, Ross Sea, Antarctica. These stations were deployed for a 60-day period in 2003/4. The noise source was associated with constant collisions between C16 and a neighboring iceberg, B15A, which was continually being driven into the northeast edge of C16 by ocean tides. The most significant modes of ambient noise transmission were found to be (1) hydroacoustic modes that bounce off the seabed below the iceberg, and (2) flexural-gravity waves that involve the flexural rigidity of the ice layer. The technique used in the study (and in similar studies of the Amery Ice Shelf reported by Zhan and others) provides a new method for studying floating ice with high sensitivity to factors that control hydroacoustic propagation over long distances. It is possible that secular changes in the sub ice ocean layer (such as changes caused by decreasing ice thickness over time) can be observed using ambient noise correlation similar to that performed here. This suggests a way in which seismic observations can constrain variables that characterize how floating ice, and in particular floating ice shelves, buttress glaciers and ice streams that discharge into the ocean.

  3. Radionuclides in ornithogenic sediments as evidence for recent warming in the Ross Sea region, Antarctica.

    PubMed

    Nie, Yaguang; Xu, Liqiang; Liu, Xiaodong; Emslie, Steven D

    2016-07-01

    Radionuclides including (210)Pb, (226)Ra and (137)Cs were analyzed in eight ornithogenic sediment profiles from McMurdo Sound, Ross Sea region, East Antarctica. Equilibration between (210)Pb and (226)Ra were reached in all eight profiles, enabling the determination of chronology within the past two centuries through the Constant Rate of Supply (CRS) model. Calculated fluxes of both (210)Pb and (137)Cs varied drastically among four of the profiles (MB4, MB6, CC and CL2), probably due to differences in their sedimentary environments. In addition, we found the flux data exhibiting a clear decreasing gradient in accordance with their average deposition rate, which was in turn related to the specific location of the profiles. We believe this phenomenon may correspond to global warming of the last century, since warming-induced surface runoff would bring more inflow water and detritus to the coring sites, thus enhancing the difference among the profiles. To verify this hypothesis, the deposition rate against age of the sediments was calculated based on their determined chronology, which showed ascending trends in all four profiles. The significant increase in deposition rates over the last century is probably attributable to recent warming, implying a potential utilization of radionuclides as environmental indicators in this region. PMID:26999368

  4. What is the Age and Origin of the Spherule Bearing Layer in some Ross Sea Cores?

    NASA Astrophysics Data System (ADS)

    Yeh, C.; Abbott, D. H.; Anders, M. H.; Breger, D.

    2012-12-01

    L.P. Khyranina (1985) was the first to suggest that there were two structures present on the Antarctic continental shelf beneath the Ross Sea. One was the ~100 km Bowers impact crater candidate. However, there was no solid evidence that proved an extraterrestrial impact produced the Bowers structure. Debate has ensued for decades on whether the Bowers structure was an impact crater. Now we have come close to finding an answer. We used core samples taken near the crater and sieved into four size fractions (>250,>125,>63,>38 μm). Impact ejecta candidates were then picked from cores ELT 32-08, ELT 32-03, ELT 32-43, ELT 32-06, DSDP 273, DSDP 274, and NPB 95-01 39KC and were analyzed for chemical composition and physical features. All but DSDP site 274 contain pure SiO2 glasses that resemble tektites. We also found candidates for flow textured impact glass and shocked quartz. This led us to conclude that the origin of the spherule-bearing layer was from an impact. With the use of dated core NBP 95-01 39KC, we have constrained the age to lie between 7,305±80 BP and 11,150±95 BP (corrected radiocarbon ages) (Cunningham et al., 1999).

  5. From warm to cold: migration of Adélie penguins within Cape Bird, Ross Island

    PubMed Central

    Nie, Yaguang; Sun, Liguang; Liu, Xiaodong; Emslie, Steven D.

    2015-01-01

    Due to their sensitivity to environmental change, penguins in Antarctica are widely used as bio-indicators in paleoclimatic research. On the basis of bio-element assemblages identified in four ornithogenic sediment profiles, we reconstructed the historical penguin population change at Cape Bird, Ross Island, for the past 1600 years. Clear succession of penguin population peaks were observed in different profiles at about 1400 AD, which suggested a high probability of migration within this region. The succession was most obviously marked by a sand layer lasting from 1400 to 1900 AD in one of the analyzed profiles. Multiple physical/chemical parameters indicated this sand layer was not formed in a lacustrine environment, but was marine-derived. Both isostatic subsidence and frequent storms under the colder climatic condition of the Little Ice Age were presumed to have caused the abandonment of the colonies, and we believe the penguins migrated from the coastal area of mid Cape Bird northward and to higher ground as recorded in the other sediment profiles. This migration was an ecological response to global climate change and possible subsequent geological effects in Antarctica. PMID:26113152

  6. Antimicrobial Activity of Monoramnholipids Produced by Bacterial Strains Isolated from the Ross Sea (Antarctica) †

    PubMed Central

    Tedesco, Pietro; Maida, Isabel; Palma Esposito, Fortunato; Tortorella, Emiliana; Subko, Karolina; Ezeofor, Chidinma Christiana; Zhang, Ying; Tabudravu, Jioji; Jaspars, Marcel; Fani, Renato; de Pascale, Donatella

    2016-01-01

    Microorganisms living in extreme environments represent a huge reservoir of novel antimicrobial compounds and possibly of novel chemical families. Antarctica is one of the most extraordinary places on Earth and exhibits many distinctive features. Antarctic microorganisms are well known producers of valuable secondary metabolites. Specifically, several Antarctic strains have been reported to inhibit opportunistic human pathogens strains belonging to Burkholderia cepacia complex (Bcc). Herein, we applied a biodiscovery pipeline for the identification of anti-Bcc compounds. Antarctic sub-sea sediments were collected from the Ross Sea, and used to isolate 25 microorganisms, which were phylogenetically affiliated to three bacterial genera (Psychrobacter, Arthrobacter, and Pseudomonas) via sequencing and analysis of 16S rRNA genes. They were then subjected to a primary cell-based screening to determine their bioactivity against Bcc strains. Positive isolates were used to produce crude extracts from microbial spent culture media, to perform the secondary screening. Strain Pseudomonas BNT1 was then selected for bioassay-guided purification employing SPE and HPLC. Finally, LC-MS and NMR structurally resolved the purified bioactive compounds. With this strategy, we achieved the isolation of three rhamnolipids, two of which were new, endowed with high (MIC < 1 μg/mL) and unreported antimicrobial activity against Bcc strains. PMID:27128927

  7. From warm to cold: migration of Adélie penguins within Cape Bird, Ross Island.

    PubMed

    Nie, Yaguang; Sun, Liguang; Liu, Xiaodong; Emslie, Steven D

    2015-01-01

    Due to their sensitivity to environmental change, penguins in Antarctica are widely used as bio-indicators in paleoclimatic research. On the basis of bio-element assemblages identified in four ornithogenic sediment profiles, we reconstructed the historical penguin population change at Cape Bird, Ross Island, for the past 1600 years. Clear succession of penguin population peaks were observed in different profiles at about 1400 AD, which suggested a high probability of migration within this region. The succession was most obviously marked by a sand layer lasting from 1400 to 1900 AD in one of the analyzed profiles. Multiple physical/chemical parameters indicated this sand layer was not formed in a lacustrine environment, but was marine-derived. Both isostatic subsidence and frequent storms under the colder climatic condition of the Little Ice Age were presumed to have caused the abandonment of the colonies, and we believe the penguins migrated from the coastal area of mid Cape Bird northward and to higher ground as recorded in the other sediment profiles. This migration was an ecological response to global climate change and possible subsequent geological effects in Antarctica. PMID:26113152

  8. Observations of Low Frequency Solar Radio Bursts from the Rosse Solar-Terrestrial Observatory

    NASA Astrophysics Data System (ADS)

    Zucca, P.; Carley, E. P.; McCauley, J.; Gallagher, P. T.; Monstein, C.; McAteer, R. T. J.

    2012-10-01

    The Rosse Solar-Terrestrial Observatory (RSTO; http://www.rosseobservatory.ie) was established at Birr Castle, Co. Offaly, Ireland (53°05'38.9″, 7°55'12.7″) in 2010 to study solar radio bursts and the response of the Earth's ionosphere and geomagnetic field. To date, three Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy in Transportable Observatory (CALLISTO) spectrometers have been installed, with the capability of observing in the frequency range of 10 - 870 MHz. The receivers are fed simultaneously by biconical and log-periodic antennas. Nominally, frequency spectra in the range of 10 - 400 MHz are obtained with four sweeps per second over 600 channels. Here, we describe the RSTO solar radio spectrometer set-up, and present dynamic spectra of samples of type II, III and IV radio bursts. In particular, we describe the fine-scale structure observed in type II bursts, including band splitting and rapidly varying herringbone features.

  9. Active and Passive Microwave Determination of the Circulation and Characteristics of Weddell and Ross Sea Ice

    NASA Technical Reports Server (NTRS)

    Drinkwater, Mark R.; Liu, Xiang

    2000-01-01

    A combination of satellite microwave data sets are used in conjunction with ECMWF (Medium Range Weather Forecasts) and NCEP (National Center for Environment Prediction) meteorological analysis fields to investigate seasonal variability in the circulation and sea-ice dynamics of the Weddell and Ross Seas. Results of sea-ice tracking using SSM/I (Special Sensor Microwave Imager), Scatterometer and SAR images are combined with in-situ data derived from Argos buoys and GPS drifters to validate observed drift patterns. Seasonal 3-month climatologies of ice motion and drift speed variance illustrate the response of the sea-ice system to seasonal forcing. A melt-detection algorithm is used to track the onset of seasonal melt, and to determine the extent and duration of atmospherically-led surface melting during austral summer. Results show that wind-driven drift regulates the seasonal distribution and characteristics of sea-ice and the intensity of the cyclonic Gyre circulation in these two regions.

  10. Unusual biogenic calcite structures in two shallow lakes, James Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Elster, J.; Nedbalová, L.; Vodrážka, R.; Láska, K.; Haloda, J.; Komárek, J.

    2015-08-01

    The floors of two shallow endorheic lakes, located on volcanic surfaces on James Ross Island, are covered with calcareous organosedimentary structures. Their biological and chemical composition, lake water characteristics, and seasonal variability of the thermal regime are introduced. The lakes are frozen down to the bottom eight-nine months per year and their water chemistry is characterized by low conductivity and neutral to slightly alkaline pH. The photosynthetic microbial mat is composed of filamentous cyanobacteria and microalgae that are considered to be Antarctic endemic species. The mucilaginous black biofilm is covered by green spots formed by a green microalga and the macroscopic structures are packed together with fine material. Thin sections consist of rock substrate, soft biofilm, calcite spicules and mineral grains originating from different sources. The morphology of the spicules is typical of calcium carbonate monocrystals having a layered structure and worn surface, which reflect growth and degradation processes. The spicules chemical composition and structure correspond to pure calcite. Lakes age, altitude, morphometry, geomorphological and hydrological stability, including low sedimentation rates, together with thermal regime predispose the existence of this community. We hypothesize that the precipitation of calcite is connected with the photosynthetic activity of the green microalgae that were not recorded in any other lake in the region. This study has shown that the unique community producing biogenic calcite spicules is quite different to any yet described.

  11. Sensitivity of coastal polynyas and high-salinity shelf water production in the Ross Sea, Antarctica, to the atmospheric forcing

    NASA Astrophysics Data System (ADS)

    Mathiot, Pierre; Jourdain, Nicolas C.; Barnier, Bernard; Gallée, Hubert; Molines, Jean Marc; Le Sommer, Julien; Penduff, Thierry

    2012-05-01

    Coastal polynyas around Antarctica are the place of intense air-sea exchanges which eventually lead to the formation of high-salinity shelf waters (HSSW) over continental shelves. Here, the influence of atmospheric forcing on coastal polynyas in the Ross Sea is studied by contrasting the response of a regional ocean/sea-ice circulation model to two different atmospheric forcing sets. A first forcing (DFS3) is based on ERA40 atmospheric surface variables and satellite products. A second forcing (MAR) is produced on the basis of ERA40 with a dynamical downscaling procedure. As compared to DFS3, MAR forcing is shown to improve substantially the representation of small-scale patterns of coastal winds with stronger katabatic winds along the coast. The response of the ocean/sea-ice model to the two forcing sets shows that the MAR forcing improves substantially the geographical distribution of polynyas in the Ross Sea. With the MAR forcing, the polynya season is also shown to last longer with a greater ice-production rate. As a consequence, a greater flow of dense water out of the polynyas is found with the MAR forcing and the properties of HSSW are notably improved as compared to the DFS3 forcing. The factors contributing to the activity of Terra Nova Bay and Ross Ice Shelf polynyas in the model are studied in detail. The general picture that emerges from our simulations is that the properties of HSSW are mostly set by brine rejection when the polynya season resume. We found that coastal polynyas in the Ross Sea export about 0.4 Sv of HSSW which then flows along three separate channels over the Ross Shelf. A 6-month time lag is observed between the peak of activity of polynyas and the maximum transport across the sills in the channels with a maximum transport of about 1 Sv in February. This lag corresponds to the time it takes to the newly formed HSSW to spread from the polynya to the sills (at a speed of nearly 2 cm s-1).

  12. Deuterium excess as a proxy for sea ice extent in the western Ross Sea, Antarctica, 1882-2006

    NASA Astrophysics Data System (ADS)

    Sinclair, K. E.; Bertler, N.; Zwartz, D.; Trompetter, B.; Millet, M.; Davy, P.

    2011-12-01

    Deuterium excess in a high-resolution ice core extracted from the Whitehall Glacier (WHG) is highly sensitive to sea ice extent since observations began in 1979. Seasonal sea ice extent has increased significantly in the Ross Sea since 1995, creating a dipole between the Ross Sea and the Amundsen and Bellinghausen Sea Coasts, which have experienced significant sea ice loss. The reasons for the spatial differences in sea ice anomalies is thought to be primarily related to the phase of the Southern Annular Mode (SAM), the primary climate driver in this sector of Antarctica, and the complex interactions of SAM with the El Niño-Southern Oscillation (ENSO). A positive phase of SAM leads to deeper low pressure anomalies in the Amundsen Sea; cooler and stronger southerly winds in the western Ross Sea, and wind-driven sea ice advance, particularly when it is reinforced by La Nina conditions. In the WHG ice core, deuterium excess has mean values of 9.5 per mil from 1979 until 1994 and 5.2 per mil after 1995. This ~5 per mil shift is concurrent with a change from negative to positive sea ice extent anomalies in the Ross Sea and a concurrent decrease in marine trace elements (Na, Mg, V, Rb). We argue that increased southerly winds since 1995 (related to a more positive SAM) have increased the area of the Ross Sea and Terra Nova Bay polynas resulting in increased sea ice extent. Because sea surface temperatures (SST) are very low over these polynas, particularly in the austral autumn and winter, the deuterium excess signal at the Whitehall Glacier is highly sensitive to the amount of local moisture input and the seasonality of this moisture contribution. Increased local moisture, with low SST, results in low deuterium excess and therefore an inverse relationship with sea ice extent. In the context of the 125-year span of the WHG record, (1882-2006), deuterium excess is markedly high (and sea ice coverage is therefore expected to have been anomalously low) in the 1950s, '60s

  13. Monitoring of land-based glaciers on James Ross Island, Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Laska, Kamil; Nyvlt, Daniel; Engel, Zbynek; Stachon, Zdenek

    2015-04-01

    Antarctic Peninsula has been considered one of the most rapidly warming parts of our planet during the second half of the 20th century. Therefore, James Ross Island located near the northern tip of the Antarctic Peninsula, represents a unique place to study the sensitivity of glacier systems to regional atmospheric warming. Since 2006, an integrated multidisciplinary study of glaciers and terrestrial ecosystems has been carried out in the northern part of Ulu Peninsula, James Ross Island. In this contribution, glacier monitoring network consisting of four dominant land-based glaciers at the Ulu Peninsula is presented. Davies Dome (DD) is an ice dome, which originates on the surface of a flat volcanic mesa at >400 m a.s.l. and terminates as a single 700 m wide outlet in Whisky Bay. In 2006, Davies Dome had an area of 6.5 km2 and lay in the altitude range 0-514 m a.s.l. Whisky Glacier (WG) is a cold-based land-terminating valley glacier, which is surrounded by an extensive area of debris-covered ice. WG covered an area of 2.4 km2 and ranged from 215 to 520 m a.s.l. Triangular Glacier (TG) is a southwest-facing land-terminating glacier with an area of 0.6 km2 ranging from 302 to 107 m a.s.l. with well-developed ice-cored terminal moraine. San Jose Glacier (SJG) is a south-facing land-terminating piedmont glacier rejuvenated from the above lying Lachman Crags Dome (~640 m a.s.l.). SJG covers an area of 0.6 km2 and extends between 138 and 310 m a.s.l. Moreover, monitoring network consists of five automatic weather stations (AWS) placed in the central and marginal parts of the selected glaciers. Each AWS was equipped with the EMS33 air temperature and humidity probes placed inside the radiation shields. Apart from that, additional instruments, e.g. albedometer, propeller anemometer, snow depth sensors were installed on the central part of DD and WG. Since 2009, annual mass balance measurements have been realized on the DD, WG and TG glaciers. In 2010, ice thickness and

  14. Ice shelf structure derived from dispersion curve analysis of ambient seismic noise, Ross Ice Shelf, Antarctica

    NASA Astrophysics Data System (ADS)

    Diez, A.; Bromirski, P. D.; Gerstoft, P.; Stephen, R. A.; Anthony, R. E.; Aster, R.; Cai, C.; Nyblade, A.; Wiens, D. A.

    2016-02-01

    An L-configured, three-component short period seismic array was deployed on the Ross Ice Shelf, Antarctica during November 2014. Polarization analysis of ambient noise data from these stations shows linearly polarized waves for frequency bands between 0.2-2 Hz. A spectral peak at about 1.6 Hz is interpreted as the resonance frequency of the water column, and is used to estimate the water layer thickness below the ice shelf. The frequency band from 4 to 18 Hz is dominated by Rayleigh and Love waves propagating from the north that, based on daily temporal variations, we conclude were generated by field camp activity. Frequency-slowness plots were calculated using beamforming. Resulting Love and Rayleigh wave dispersion curves were inverted for the shear wave velocity profile within the firn and ice to ˜150 m depth. The derived density profile allows estimation of the pore close-off depth and the firn-air content thickness. Separate inversions of Rayleigh and Love wave dispersion curves gives different shear-wave velocity profiles within the firn. We attribute this difference to an effective anisotropy due to fine layering. The layered structure of firn, ice, water, and the seafloor results in a characteristic dispersion curve below 7 Hz. Forward modeling the observed Rayleigh wave dispersion curves using representative firn, ice, water, sediment structures indicates that Rayleigh waves are observed when wavelengths are long enough to span the distance from the ice shelf surface to the seafloor. The forward modeling shows that analysis of seismic data from an ice shelf provides the possibility of resolving ice shelf thickness, water column thickness, and the physical properties of the ice shelf and underlying seafloor using passive-source seismic data.

  15. Photosynthesis-irradiance responses in the Ross Sea, Antarctica: a meta-analysis

    NASA Astrophysics Data System (ADS)

    Smith, W. O., Jr.; Donaldson, K. A.

    2014-12-01

    A meta-analysis of photosynthesis/irradiance measurements was completed using data from the Ross Sea, Antarctica. A total of 544 independent measurements were included. PsB, the maximum, chlorophyll-specific, irradiance-saturated rate of photosynthesis, averaged 1.07 ± 0.060 μg C (μg chl)-1 h-1. Light-limited photosynthetic rates (α) averaged 0.03 ± 0.023 μg C (μg chl)-1 h-1 μmol photons m-2 s-1)-1. Significant variations in PsB and α were found as a function of season, with spring maximum photosynthetic rates being 59% greater than those in summer. Similarly, α values were 48% greater in spring. There was no detectable effect of space on the photosynthetic parameters, and temperature and macronutrient (NO3) concentrations also did not exert a strong influence. However, irradiance, dissolved iron concentrations, and carbon dioxide concentrations when altered under controlled conditions exerted significant influences on photosynthetic parameters. Specifically, reduced irradiance resulted in decreased PsB and α values, whereas reduced iron concentrations were associated with increased PsB and α values. Increased CO2 concentrations also resulted in significantly increased PsB and α values. No significant difference was detected between stations dominated by diatoms and those dominated by the haptophyte Phaeocystis antarctica. The meta-analysis generally confirms the photosynthetic rates predicted from global analyses that are based solely on temperature and irradiance availability, but suggests that for more accurate predictions of the productivity of polar systems a more detailed model that includes temporal effects of photosynthetic parameters will be required.

  16. Photosynthesis-irradiance responses in the Ross Sea, Antarctica: a meta-analysis

    NASA Astrophysics Data System (ADS)

    Smith, W. O., Jr.; Donaldson, K.

    2015-06-01

    A meta-analysis of photosynthesis-irradiance measurements was completed using data from the Ross Sea, Antarctica, using a total of 417 independent measurements. PmB, the maximum, chlorophyll-specific, irradiance-saturated rate of photosynthesis, averaged 1.1 ± 0.06 μg C (μg Chl)-1 h-1. Light-limited, chlorophyll-specific photosynthetic rates (αB) averaged 0.030 ± 0.023 μg C (μg Chl)-1 h-1 (μmol quanta m-2 s-1)-1. Significant variations in PmB and αB were found as a function of season, with spring maximum photosynthetic rates being 60% greater than those in summer. Similarly, α values were 48% greater in spring. There was no detectable effect of sampling location on the photo-synthetic parameters, and temperature and macronutrient (NO3) concentrations also did not have an influence. However, irradiance and carbon dioxide concentrations, when altered under controlled conditions, exerted significant influences on photosynthetic parameters. Specifically, reduced irradiance resulted in significantly decreased PmB and increased αB values, and increased CO2 concentrations resulted in significantly increased PmB and αB values. Comparison of photosynthetic parameters derived at stations where iron concentrations were above and below 0.1 nM indicated that reduced iron levels were associated with significantly increased PmB values, confirming the importance of iron within the photosynthetic process. No significant difference was detected between stations dominated by diatoms and those dominated by the haptophyte Phaeocystis antarctica. The meta-analysis confirms the photosynthetic rates predicted from global analyses that are based solely on temperature and irradiance availability, but suggests that, for more accurate predictions of productivity in polar systems, a more detailed model that includes temporal effects of photosynthetic parameters will be required.

  17. Biochemical and microbial features of shallow marine sediments along the Terra Nova Bay (Ross Sea, Antarctica)

    NASA Astrophysics Data System (ADS)

    Baldi, Franco; Marchetto, Davide; Pini, Francesco; Fani, Renato; Michaud, Luigi; Lo Giudice, Angelina; Berto, Daniela; Giani, Michele

    2010-09-01

    Shallow marine sediments were collected from seven stations (three of which located at Gerlache Inlet, two at Tethys Bay, one at Adelie Cove and one just beneath the Italian Research Base) along the Terra Nova Bay coast (Ross Sea, Antarctica). Their chemical, biochemical and microbiological properties were studied in order to provide further insights in the knowledge of this Antarctic benthic ecosystem. Overall, the organic carbon (OC) represented the major fraction of total carbon (TC) and displayed concentrations similar to or slightly lower than those previously measured in Antarctic bottom sediments. The biopolymeric carbon within OC ranged from 4.1% to 19.9% and showed a wide trophic range (65-834 μg g -1 d.w.). Proteins (PRT) represented on average the main biochemical class contributing to labile organic carbon, followed by lipids (LIP) and carbohydrates (CHO). The activity of aminopeptidase, β- D-glucosidase, alkaline phosphatase and esterase was checked, giving the highest values at Tethys Bay and at the deepest water sediments. The principal component analysis, which was computed considering physical, chemical (elemental and biochemical sedimentary composition) and microbiological parameters (including bacterial abundance, ectoenzymatic activities, T-RFs richness and diversity indices), allowed to obtain two main clusters ("Tethys Bay" and "other stations"). Based on data obtained, two representative 16S rRNA clone libraries using samples from Tethys Bay and Gerlache Inlet were constructed. The sequences of 171 clones were compared to those available in public databases to determine their approximate phylogenetic affiliations. Both aerobic and anaerobic bacteria were disclosed, with the majority of them affiliated with the Gamma- and Deltaproteobacteria, Bacteroidetes and Acidobacteria. The occurrence of strictly anaerobic bacteria suggests that sediments might also undergo anoxic conditions that, in turn, could favor the accumulation of PRT in respect

  18. Effects of early seafloor processes on skeletal carbonate deposits, Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Frank, T. D.; Färber, C.; James, N. P.

    2015-12-01

    Although relatively rare in space and time, skeletal carbonates deposited in glacially influenced settings hold great potential for improving understanding of the oceanography of the high latitudes. Accumulation in an environment where ocean water is close to carbonate undersaturation has major implications for component preservation and thus potential translation into the geological record. To understand the effects of early seafloor processes, we investigate Quaternary deposits of carbonates recovered in piston cores from the Ross Sea, Antarctica. In this setting, unconsolidated skeletal gravels and sands mantle areas of the outer shelf swept by bottom currents and beneath a zone of high primary productivity. Deposits are dominated locally by either stylasterine hydrocorals, barnacles, or bryozoans, comprising assemblages that differ from those living today. Radiocarbon ages indicate that carbonate factories were most prolific during the leadup to the Last Glacial Maximum, when sediment input was minimized, and have been mostly dormant since. Although there is little evidence for dissolution, skeletal debris is highly fragmented, abraded, and intensely bioeroded. The degree of destruction by these processes is highly selective amongst taxa, with skeletal structure influencing resistance to physical and biological breakdown. Overlapping generations of endolithic borings reflect moderate to high nutrient availability and repeated exposure of grains to infestation. Preserved grains are entirely calcitic and lack evidence of inorganic precipitation, implying potential taphonomic loss of aragonitic components. Observations indicate that seafloor processes in this setting combine to destroy a significant amount of carbonate as well as alter original depositional textures of deposits. Interpretations of ancient glaciomarine carbonates must consider the potential for significant biases created by destructive early seafloor processes.

  19. Reconstructing Holocene conditions under ice in the Ross Sea and in the Southern Ocean using barnacles

    NASA Astrophysics Data System (ADS)

    Burgess, S. N.; Henderson, G. M.; Hall, B. L.

    2009-12-01

    Paleoclimate archives that capture annual and subannual resolution marine conditions outside the tropics are not common but would be highly desirable. This study demonstrates the potential of barnacles for such purposes and applies them to paleoceanographic reconstruction under the McMurdo ice shelf and in the Southern Ocean. Most of the Bathylasma samples used in this study grew in the Ross Sea and range in age between modern samples (used for calibration) and Holocene samples which were collected on the surface of the McMurdo Ice Shelf, having been entrained at the grounding line and moved through the ice by surface ablation and further basal freezing. Like other barnacles, this species secretes a robust low-Mg calcite shell with distinct growth increments on the external surface indicating growth durations of several decades. Barnacle shells were subsampled at high resolution (60 μm) for δ18O and δ13C analysis and dated by 14C. Measured δ18O values indicate that Bathylasma calcifies close to equilibrium with ambient seawater and those of old (>200kyr) samples suggest little or no diagenesis. These features make barnacles a promising archive for reconstruction of past ocean conditions. Variations in barnacle δ18O within each plate and between plates reflect changes in δ18O of the seawater, and allow some assessment of the salinity under the ice shelf. Salinities are lowered by addition of meltwaters, but the barnacle data suggest this lowering does not go below 33‰. Salinity near the grounding line shows both temporal and spatial variability. These data indicate that Bathylasma can provide valuable paleoclimate information at subannual resolution for shallow/intermediate water depths and regions such as Antarctica that play an important role in the climate system. We are now exploring this potential to investigate intermediate water conditions in the South Pacific during the last glacial using samples from seamounts on the Macquarie Ridge and south of

  20. Ice shelf structure derived from dispersion curve analysis of ambient seismic noise, Ross Ice Shelf, Antarctica

    NASA Astrophysics Data System (ADS)

    Diez, A.; Bromirski, P. D.; Gerstoft, P.; Stephen, R. A.; Anthony, R. E.; Aster, R. C.; Cai, C.; Nyblade, A.; Wiens, D. A.

    2016-05-01

    An L-configured, three-component short period seismic array was deployed on the Ross Ice Shelf, Antarctica during November 2014. Polarization analysis of ambient noise data from these stations shows linearly polarized waves for frequency bands between 0.2 and 2 Hz. A spectral peak at about 1.6 Hz is interpreted as the resonance frequency of the water column and is used to estimate the water layer thickness below the ice shelf. The frequency band from 4 to 18 Hz is dominated by Rayleigh and Love waves propagating from the north that, based on daily temporal variations, we conclude were generated by field camp activity. Frequency-slowness plots were calculated using beamforming. Resulting Love and Rayleigh wave dispersion curves were inverted for the shear wave velocity profile within the firn and ice to ˜150 m depth. The derived density profile allows estimation of the pore close-off depth and the firn-air content thickness. Separate inversions of Rayleigh and Love wave dispersion curves give different shear wave velocity profiles within the firn. We attribute this difference to an effective anisotropy due to fine layering. The layered structure of firn, ice, water and the seafloor results in a characteristic dispersion curve below 7 Hz. Forward modelling the observed Rayleigh wave dispersion curves using representative firn, ice, water and sediment structures indicates that Rayleigh waves are observed when wavelengths are long enough to span the distance from the ice shelf surface to the seafloor. The forward modelling shows that analysis of seismic data from an ice shelf provides the possibility of resolving ice shelf thickness, water column thickness and the physical properties of the ice shelf and underlying seafloor using passive-source seismic data.

  1. Observations of the Summertime Boundary Layer over the Ross Ice Shelf, Antarctica Using SUMO UAVs

    NASA Astrophysics Data System (ADS)

    Nigro, M. A.; Cassano, J. J.; Jolly, B.; McDonald, A.

    2014-12-01

    During January 2014 Small Unmanned Meteorological Observer (SUMO) unmanned aerial vehicles (UAVs) were used to observe the boundary layer over the Ross Ice Shelf, Antarctica. A total of 41 SUMO flights were completed during a 9-day period with a maximum of 11 flights during a single day. Flights occurred as frequently as every 1.5 hours so that the time evolution of the boundary layer could be documented. On almost all of the flights the boundary layer was well mixed from the surface to a depth of less than 50 m to over 350 m. The depth of the well-mixed layer was observed to both increase and decrease over the course of an individual day suggesting that processes other than entrainment were altering the boundary layer depth. The well-mixed layer was observed to both warm and cool during the field campaign indicating that advective processes as well as surface fluxes were acting to control the temporal evolution of the boundary layer temperature. Only a small number of weakly stably stratified boundary layers were observed. Strong, shallow inversions, of up to 6 K, were observed above the top of the boundary layer. Observations from a 30 m automatic weather station and two temporary automatic weather stations 10 km south and west of the main field campaign location provide additional data for understanding the boundary layer evolution observed by the SUMO UAVs during this 9-day period. This presentation will discuss the observed evolution of the summertime boundary layer as well as comment on lessons learned operating the SUMO UAVs at a remote Antarctic field camp.

  2. Depth profiles of bacterioplankton assemblages and their activities in the Ross Sea

    NASA Astrophysics Data System (ADS)

    Celussi, Mauro; Cataletto, Bruno; Fonda Umani, Serena; Del Negro, Paola

    2009-12-01

    The identification of bacterial community structure has led, since the beginning of the 1990s, to the idea that bacterioplankton populations are stratified in the water column and that diverse lineages with mostly unknown phenotypes dominate marine microbial communities. The diversity of depth-related assemblages is also reflected in their patterns of activities, as bacteria affiliated to different groups can express different activities in a given ecosystem. We analysed bacterial assemblages (DGGE fingerprinting) and their activities (prokaryotic carbon production, protease, phosphatase, chitinase, beta-glucosidase and lipase activities) in two areas in the Ross Sea, differing mainly in their productivity regime: two stations are located in the Terra Nova Bay polynya area (highly productive during summer) and two close to Cape Adare (low phytoplankton biomass and activity). At every station a pronounced stratification of bacterial assemblages was identified, highlighting epipelagic communities differing substantially from the mesopelagic and the bathypelagic communities. Multivariate analysis suggested that pressure and indirectly light-affected variables (i.e. oxygen and fluorescence) had a great effect on the bacterial communities outcompeting the possible influences of temperature and dissolved organic carbon concentration. Generally activities decreased with depth even though a signal of the Circumpolar Deep Water (CDW) at one of the northern stations corresponded to an increase in some of the degradative activities, generating some 'hot spots' in the profile. We also found that similar assemblages express similar metabolic requirements reflected in analogous patterns of activity (similar degradative potential and leucine uptake rate). Furthermore, the presence of eukaryotic chloroplasts' 16S rDNA in deep samples highlighted how in some cases the dense surface-water formation (in this case High Salinity Shelf Water—HSSW) and downwelling can affect, at least

  3. Direct Effect of Carbon Dioxide Concentration on Phytoplankton Community Structure in the Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Riesselman, C. R.; Tortell, P. D.; Payne, C. D.; Dunbar, R. B.; Ditullio, G. R.

    2006-12-01

    As the largest high-nutrient low-chlorophyll (HNLC) region on the planet, the Southern Ocean plays a critical role in global biogeochemical cycling and climate modulation. Primary productivity and phytoplankton community structure in the waters surrounding Antarctica have demonstrated unique sensitivity to small changes in major and trace element availability and vertical mixing. However, the capacity of changing atmospheric CO2 to restructure Antarctic phytoplankton communities has only recently been proposed. During the austral summer of 2005-2006, the "Controls on Ross Sea Algal Community Structure" (CORSACS) project performed an integrated series of shipboard incubations coupled with polynya water column sampling designed to investigate the interplay of iron, light, and CO2 levels as determinants of primary production and phytoplankton community structure. Results from the CORSACS CO2 manipulation incubation experiment demonstrate substantial shifts in the taxonomic distribution of phytoplankton exposed to an experimental CO2 gradient. Triplicate semi-continuous culture bottles were bubbled with air mixtures containing 100, 370, and 800 ppm CO2, designed to approximate bloom conditions under glacial, modern, and projected future levels of carbon dioxide. At the conclusion of the 18-day incubation, the 100 ppm community was dominated by the small, finely silicified pennate diatom Pseudonitzschia subcurvata, while the abundance of larger, colonial Chaetoceros species increased significantly in the 800 ppm community. These results represent the first evidence that perturbations in atmospheric CO2 have the potential to reorganize phytoplankton community structure in the Southern Ocean, and have implications for both the glacial productivity paradox and the future of polar trophic structure.

  4. Neogene Fault and Feeder Dike Patterns in the Western Ross Sea

    NASA Astrophysics Data System (ADS)

    Magee, W. R.; Wilson, T. J.

    2010-12-01

    In Antarctica, where much of the continent is covered by water and ice, geophysical data from the Antarctic submarine continental shelf is a fundamental part of reconstructing geological history. Multibeam sonar from the western Ross Sea has revealed elongate volcanic edifices and fields of elongate submarine hills on the seafloor. Origin of the submarine hills as carbonate mounds and drumlins have been proposed. The hills are up to ~8000m long and ~3500m wide, and rise 50-100m above the seafloor. Morphometric analysis of the hills shows they are elongate, with axial ratios ranging from 1.2:1 to 2:1, and some hills are linked to form elongate ridges. Seismic profiles show significant pull-ups directly below the hills, consistent with narrow, higher-density magmatic bodies; thus we favor an origin as volcanic seamounts above subsurface feeder dikes. If this volcanic hypothesis is correct, feeder dikes below the hills and elongate volcanic ridges may document magmatically-forced extension within the Terror Rift. The seamount field forms part of a regional en echelon array of volcanic ridges extending NNW from Beaufort Island toward Drygalski Ice Tongue. The ridges and elongate seamount cluster trend NNE, subparallel to mapped fault trends in this sector of the Terror Rift. This geometry is compatible with right-lateral transtension along this zone, as previously proposed for the Terror Rift as a whole. Volcanic islands and dredged volcanic ridges within the en echelon array are dated at ~7-4 Ma, implying Neogene deformation. We are completing a detailed analysis of orientation patterns and cross-cutting relations between faults and volcanic hills and their feeder systems to test this model for Neogene rift kinematics.

  5. Comparative effects of in ovo versus subcutaneous administration of the Marek's disease vaccine and pre-placement holding time on the early post-hatch quality of Ross × Ross 708 broiler chicks.

    PubMed

    Peebles, E D; Barbosa, T M; Cummings, T S; Dickson, J; Womack, S K

    2016-09-01

    Effects of method of administration [moa; in ovo (i.o.) or s.c.] of the Marek's disease vaccine and pre-placement holding time (pht) on early post-hatch male broiler chick quality was investigated. Sixty-five Ross × Ross 708 broiler hatching eggs were randomly set in each of 15 replicate trays (blocks) belonging to each of 4 pre-assigned moa and pht treatment combinations (3,900 total eggs) in a single stage Jamesway incubator. Eggs that were i.o.-vaccinated received injections at 18 d of incubation and male chicks from eggs that were not i.o.-injected were vaccinated by s.c. injection at hatch. The i.o. injections (50 μL) were delivered by a commercial multi-egg injector and the s.c. injections (200 μL) were delivered by an automatic pneumatic s.c. injector. Male chicks from each moa group also were subjected to either a 4 or 18 h pht. At hatch and placement total and yolk-free BW; body length; body mass index; yolk sac weight; yolk-free body and yolk sac weights as percentages of total BW; and yolk-free body and yolk moisture concentrations were determined. Chick BW also was determined at 7 d of age. Hatchability of fertile eggs was not affected by i.o. injection. However, at hatch, body length was increased and body mass index was decreased in response to i.o. injection. No main effect of moa or an interactive effect with pht was observed for the above variables at placement. However, body length was longer and body mass was lower in the 18 h than in the 4 h pht chicks. Placement yolk sac and body weights, and the 7 d BW of 18 h pht chicks was also lower than that of 4 h pht chicks. In conclusion, prolonging pht for 14 h adversely affected early chick quality, whereas i.o. injection did not negatively affect the early post-hatch quality of Ross × Ross 708 broiler chicks whether or not they were held for 4 or 18 h prior to placement. PMID:27143771

  6. Constraints on the last deglaciation of the Ross Sea Sector of the West Antarctic Ice Sheet (WAIS) from 10Be dating

    NASA Astrophysics Data System (ADS)

    Bill, N. S.; Clark, P. U.; Kurz, M. D.; Marcott, S. A.; Caffee, M. W.

    2014-12-01

    We present new 10Be surface exposure ages from glacial erratic boulders from several locations in McMurdo Sound in order to constrain the deglacial history of the West Antarctic Ice Sheet. Previous model and field data indicate that the present day Ross Ice Shelf was a grounded ice sheet, with the grounding line extending to near the continental shelf edge during the Last Glacial Maximum (LGM). However, the timing and rate of the last deglaciation of the Ross Sea Sector of the West Antarctic Ice Sheet remain uncertain. We sampled granitic and basaltic erratic boulders for dating with the cosmogenic nuclides 10Be and 3He; in situ 14C dating will be used to assess complex burial histories. The 10Be ages on erratics near or at the upper limit of Ross Sea Drift that do not appear to have inheritance range from 17 to 26 ka. 10Be ages from erratics below the limit of the (LGM) Ross Sea Drift suggest final deglaciation by ~11 ka. New 10Be ages from more highly weathered glacial deposits above the Ross Sea drift near Blue Glacier suggest an age range of 141 to 171 ka.

  7. Amazon River

    Atmospheric Science Data Center

    2013-04-17

    article title:  Mouth of the Amazon River     View Larger Image ... over 6450 kilometers eastward across Brazil, the Amazon River originates in the Peruvian Andes as tiny mountain streams that eventually ...

  8. Influence of the West Antarctic Ice Sheet and its collapse on the wind and precipitation regimes of the Ross Embayment

    NASA Astrophysics Data System (ADS)

    Seles, D.; Kowalewski, D. E.

    2015-12-01

    Marine Isotope Stage 31 (MIS 31) is a key analogue for current warming trends yet the extent of the East Antarctic Ice Sheet (EAIS) and the West Antarctic Ice Sheet (WAIS) during this interglacial remains unresolved. Inconsistencies persist between offshore records (suggesting the instability of WAIS) and McMurdo Dry Valley (MDV) terrestrial datasets (indicating long-term ice sheet stability). Here we use a high-resolution regional scale climate model (RegCM3_Polar) to reconstruct paleoclimate during MIS 31 (warm orbit, 400 ppm CO2) and assess changes in precipitation and winds (including katabatic) with WAIS present versus WAIS absent. The MIS 31 scenario with WAIS present resulted in minimal changes in wind magnitude compared with current climate conditions. With WAIS absent, the model predicts a decrease in coastal and highland monthly mean average wind velocities. The greatest rates of snowfall remain along the coast but shift towards higher latitudes with the interior continent remaining dry when WAIS is removed. Focusing on the Ross Embayment, this decreased monthly mean wind velocity and shift of winds to the east indicate a greater influence of offshore winds from the Ross Sea, enabling the increase of precipitation southward along the Transantarctic Mountains (TAM) (i.e. MDV). The apparent decrease of katabatic winds with no WAIS implies that offshore winds may be responsible for bringing the warmer, wetter air into the TAM. The change in wind and precipitation in the Ross Embayment and specifically the MDV highlights the impact of WAIS on Antarctic climate and its subsequent influence on the mass balance of peripheral EAIS domes (i.e. Taylor Dome). Modeling suggests that if WAIS was absent during MIS 31, we would expect (1) greater accumulation at such domes and (2) MDV terrestrial records that reflect a wetter climate, and (3) weaker winds suggesting possibly lower ablation/erosion rates compared to if WAIS was present.

  9. A flow band model of the Ross Ice Shelf, Antarctica: Response to CO sub 2 -induced climatic warming

    SciTech Connect

    Lingle, C.S.; Brown, T.J. ); Schilling, D.H. ); Fastook, J.L. ); Paterson, W.S.B. )

    1991-04-10

    A time-dependent model is applied to the Ross Ice Shelf flow band discharging ice stream B, West Antarctica. The model includes the effects of temperature, depth-dependent density, and backpressure from the coasts of the Ross embayment and Crary Ice Rise. Data from the Ross Ice Shelf Geophysical and Glaciological Survey and the Siple Coast Project are used as input data. Accuracy and stability are verified by reproducing the flow band for 10,000 model years with equilibrium distributions of accumulation, surface temperature, and basal balance. Sensitivity is tested by forcing the model with increasing accumulation rates, surface temperatures, and basal melt rates, respectively, while other factors are held constant. The response of the ice shelf to three climatic scenarios that may result from increasing carbon dioxide and trace greenhouse gases is simulated. The results range from slight thickening with moderately increased backpressure in the grounding zone to rapid thinning accompanied by rapidly decreasing backpressure during 175- to 600-year simulations, depending primarily upon whether increasing surface temperatures and accumulaton rates are accompanied by increased rates of basal melting. The central ice shelf, about 400 km upglacier from the calving front, thins by 22% in 600 years when basal melting is increased linearly to a maximum of 0.5 m/yr after 150 years, then held steady. The ice shelf thins by 40% in 175 years at the same location when basal melting is increasedlinearly to 2.0 m/yr after 150 years, then held steady. The present calculated equilibrium rate of basal melting, averaged over the bottom surface of the flow band is 0.17 m/yr.

  10. Nile River

    Atmospheric Science Data Center

    2013-04-15

    article title:  Nile River Fluctuations Near Khartoum, Sudan     ... history, the rising and falling waters of the mighty Nile River have directly impacted the lives of the people who live along its banks. ... the area around Sudan's capital city of Khartoum capture the river's dynamic nature. Acquired by the Multi-angle Imaging SpectroRadiometer ...

  11. Mississippi River

    Atmospheric Science Data Center

    2014-05-15

    article title:  Mississippi River Flooding during Spring 2001     ... South TIFF: 1024 x 724 The Mississippi River, from its source at Lake Itasca Minnesota to the Gulf of Mexico is ... 2348 miles long. Over the course of it's history, the mighty river has flooded many times. The largest flood recorded in the lower valley ...

  12. Niger River

    Atmospheric Science Data Center

    2013-04-15

    article title:  Niger River after the Rainy Season     View larger image The third largest river in Africa, the Niger, forms an inland delta in central Mali. This ... is situated near the top of the image, where the Niger River changes direction to flow more directly eastward. Six hundred years ago, ...

  13. Thermal regime of active layer at two lithologically contrasting sites on James Ross Island, Antarctic Peninsula.

    NASA Astrophysics Data System (ADS)

    Hrbáček, Filip; Nývlt, Daniel; Láska, Kamil

    2016-04-01

    Antarctic Peninsula region (AP) represents one of the most rapidly warming parts of our planet in the last 50 years. Despite increasing research activities along both western and eastern sides of AP in last decades, there is still a lot of gaps in our knowledge relating to permafrost, active layer and its thermal and physical properties. This study brings new results of active layer monitoring on James Ross Island, which is the largest island in northern AP. Its northern part, Ulu Peninsula, is the largest ice-free area (more than 200 km2) in the region. Due its large area, we focused this study on sites located in different lithologies, which would affect local thermal regime of active layer. Study site (1) at Abernethy Flats area (41 m a.s.l.) lies ~7 km from northern coast. Lithologically is formed by disintegrated Cretaceous calcareous sandstones and siltstones of the Santa Marta Formation. Study site (2) is located at the northern slopes of Berry Hill (56 m a.s.l.), about 0.4 km from northern coastline. Lithology is composed of muddy to intermediate diamictites, tuffaceous siltstones to fine grained sandstones of the Mendel Formation. Data of air temperature at 2 meters above ground and the active layer temperatures at 75 cm deep profiles were obtained from both sites in period 1 January 2012 to 31 December 2014. Small differences were found when comparing mean air temperatures and active temperatures at 5 and 75 cm depth in the period 2012-2014. While the mean air temperatures varied between -7.7 °C and -7.0 °C, the mean ground temperatures fluctuated between -6.6 °C and -6.1 °C at 5 cm and -6.9 °C and -6.0 °C at 75 cm at Abernethy Flats and Berry Hill slopes respectively. Even though ground temperature differences along the profiles weren't pronounced during thawing seasons, the maximum active layer thickness was significantly larger at Berry Hill slopes (80 to 82 cm) than at Abernethy Flats (52 to 64 cm). We assume this differences are affected by

  14. Flow of Ice near a Large Melt Channel in the Ross Ice Shelf

    NASA Astrophysics Data System (ADS)

    Conway, H.; Hindmarsh, R. C. A.; Koutnik, M. R.; Stevens, C.; Winberry, J. P.

    2014-12-01

    There is increasing evidence for the existence of large channels incised beneath ice shelves in West Antarctica. However, the genesis of these channels is still not clear. Measurements from the floating tongue of Pine Island Glacier show that sub-shelf channels formed by localized melting (Stanton et al., 2013); oceanographic models of flow in sub-ice-shelf cavities are capable of producing sub-shelf channels through non-linear feed-back mechanisms (Gladish et al. 2012; Sergienko, 2013). On the other hand, other evidence suggests that sub-shelf channels can initiate at locations where melt water beneath grounded ice crosses the grounding line (Le Brocq et al. 2013). Here we use ground-based radar to map a channel incised into the base of the Ross Ice Shelf proximal to the grounding zone of Beardmore Glacier, West Antarctica. Results show that in the grounding zone (ice thickness is 1150m), the channel is 100m deep and 0.5 km wide. On the shelf, the channel widens and deepens down stream; 8km down from the grounding line (ice thickness is 600-800 m), the channel is 200m deep and 1 km wide (see Figure); apparently in this case, the channel originates from beneath the grounded ice. Although there is some indication of radar-detected internal stratigraphy dipping toward the channels indicative of meltin, the pattern of the stratigraphy suggests significant accumulated strain (see Figure). Further, vertical strain-rates calculated from repeat measurements using phase-sensitive radar (pRES), show a more complex pattern over melt-channels than is usually assumed for ice shelves. Specifically, 57 of the 69 pRES measurements exhibit a pattern of compression in the upper 75% of the ice column and extension in the lower 25%. This observation is important because such a pattern affects the ratio of surface- to mean-velocity, which is usually assumed to be unity in shelf-mass balance calculations. FIGURE CAPTION: Unmigrated, across-channel radar profile 8km downstream from the

  15. Does body size influence nest attendance? A comparison of Ross's geese (Chen rossii) and the larger, sympatric lesser snow geese (C. caerulescens caerulescens)

    USGS Publications Warehouse

    Jonsson, J.E.; Afton, A.D.; Alisauskas, R.T.

    2007-01-01

    The body-size hypothesis predicts that nest attendance is positively related to body size among waterfowl and that recess duration is inversely related to body size. Several physiological and behavioral characteristics of Ross's geese (Chen rossii) suggest that females of this species should maintain high nest attendance despite their relatively small body size. Accordingly, we used 8-mm films to compare the incubation behavior of Ross's geese to that of the larger, closely-related lesser snow geese (C. caerulescens caerulescens; hereafter, snow geese) nesting sympatrically at Karrak lake, Nunavut, Canada in 1993. We found that nest attendance averaged 99% for both species. Our results offer no support for the body-size hypothesis. We suggest that temperature requirements of embryos in relation to short incubation duration and a low foraging efficiency of females select for high nest attendance in both snow geese and Ross's geese. ?? Dt. Ornithologen-Gesellschaft e.V. 2007.

  16. STS-55 SL-D2 MS3 Harris and MS1/PLC Ross inspect OV-102's PLB with techicians

    NASA Technical Reports Server (NTRS)

    1993-01-01

    STS-55 Spacelab Deutsche 2 (SL-D2) Mission Specialist 3 (MS3) Bernard A. Harris, Jr (center, mustache) and MS1 and Payload Commander (PLC) Jerry L. Ross (far right), wearing clean suits, inspect Columbia's, Orbiter Vehicle (OV) 102's, payload bay (PLB) equipment and experiments. Ross points to the unique support structure (USS) and its experiments in the aft PLB as Harris and Kennedy Space Center (KSC) technicians look on. The Reaction Kinetics in Glass Melts (RKGM) get away special (GAS) canister is visible at the lower right corner and the Atomic Oxygen Exposure Tray on the USS. Harris and Ross are conducting a Crew Equipment Interface Test (CEIT) of PLB equipment while OV-102 is in KSC's Orbiter Processing Facility (OPF) High Bay 2. More commonly known as the sharp edge inspection, the test provides an opportunity for a thorough inspection of the payload before flight. View provided by KSC with alternate KSC number KSC-93PC-210.

  17. Trends in the Breeding Population of Adélie Penguins in the Ross Sea, 1981–2012: A Coincidence of Climate and Resource Extraction Effects

    PubMed Central

    Lyver, Phil O’B.; Barron, Mandy; Barton, Kerry J.; Ainley, David G.; Pollard, Annie; Gordon, Shulamit; McNeill, Stephen; Ballard, Grant; Wilson, Peter R.

    2014-01-01

    Measurements of the size of Adélie penguin (Pygoscelis adeliae) colonies of the southern Ross Sea are among the longest biologic time series in the Antarctic. We present an assessment of recent annual variation and trends in abundance and growth rates of these colonies, adding to the published record not updated for more than two decades. High angle oblique aerial photographic surveys of colonies were acquired and penguins counted for the breeding seasons 1981–2012. In the last four years the numbers of Adélie penguins in the Ross and Beaufort Island colonies (southern Ross Sea metapopulation) reached their highest levels since aerial counts began in 1981. Results indicated that 855,625 pairs of Adélie penguins established breeding territories in the western Ross Sea, with just over a quarter (28%) of those in the southern portion, constituting a semi-isolated metapopulation (three colonies on Ross Island, one on nearby Beaufort Island). The southern population had a negative per capita growth rate of −0.019 during 1981–2000, followed by a positive per capita growth rate of 0.067 for 2001–2012. Colony growth rates for this metapopulation showed striking synchrony through time, indicating that large-scale factors influenced their annual growth. In contrast to the increased colony sizes in the southern population, the patterns of change among colonies of the northern Ross Sea were difficult to characterize. Trends were similar to southern colonies until the mid-1990s, after which the signal was lost owing to significantly reduced frequency of surveys. Both climate factors and recovery of whale populations likely played roles in the trends among southern colonies until 2000, after which depletion of another trophic competitor, the Antarctic toothfish (Dissostichus mawsoni), may explain the sharp increasing trend evident since then. PMID:24621601

  18. Trends in the breeding population of Adélie penguins in the Ross Sea, 1981-2012: a coincidence of climate and resource extraction effects.

    PubMed

    Lyver, Phil O'B; Barron, Mandy; Barton, Kerry J; Ainley, David G; Pollard, Annie; Gordon, Shulamit; McNeill, Stephen; Ballard, Grant; Wilson, Peter R

    2014-01-01

    Measurements of the size of Adélie penguin (Pygoscelis adeliae) colonies of the southern Ross Sea are among the longest biologic time series in the Antarctic. We present an assessment of recent annual variation and trends in abundance and growth rates of these colonies, adding to the published record not updated for more than two decades. High angle oblique aerial photographic surveys of colonies were acquired and penguins counted for the breeding seasons 1981-2012. In the last four years the numbers of Adélie penguins in the Ross and Beaufort Island colonies (southern Ross Sea metapopulation) reached their highest levels since aerial counts began in 1981. Results indicated that 855,625 pairs of Adélie penguins established breeding territories in the western Ross Sea, with just over a quarter (28%) of those in the southern portion, constituting a semi-isolated metapopulation (three colonies on Ross Island, one on nearby Beaufort Island). The southern population had a negative per capita growth rate of -0.019 during 1981-2000, followed by a positive per capita growth rate of 0.067 for 2001-2012. Colony growth rates for this metapopulation showed striking synchrony through time, indicating that large-scale factors influenced their annual growth. In contrast to the increased colony sizes in the southern population, the patterns of change among colonies of the northern Ross Sea were difficult to characterize. Trends were similar to southern colonies until the mid-1990s, after which the signal was lost owing to significantly reduced frequency of surveys. Both climate factors and recovery of whale populations likely played roles in the trends among southern colonies until 2000, after which depletion of another trophic competitor, the Antarctic toothfish (Dissostichus mawsoni), may explain the sharp increasing trend evident since then. PMID:24621601

  19. Using overlapping sonobuoy data from the Ross Sea to construct a 2D deep crustal velocity model

    NASA Astrophysics Data System (ADS)

    Selvans, M. M.; Clayton, R. W.; Stock, J. M.; Granot, R.

    2012-03-01

    Sonobuoys provide an alternative to using long streamers while conducting multi-channel seismic (MCS) studies, in order to provide deeper velocity control. We present analysis and modeling techniques for interpreting the sonobuoy data and illustrate the method with ten overlapping sonobuoys collected in the Ross Sea, offshore from Antarctica. We demonstrate the importance of using the MCS data to correct for ocean currents and changes in ship navigation, which is required before using standard methods for obtaining a 1D velocity profile from each sonobuoy. We verify our 1D velocity models using acoustic finite-difference (FD) modeling and by performing depth migration on the data, and demonstrate the usefulness of FD modeling for tying interval velocities to the shallow crust imaged using MCS data. Finally, we show how overlapping sonobuoys along an MCS line can be used to construct a 2D velocity model of the crust. The velocity model reveals a thin crust (5.5 ± 0.4 km) at the boundary between the Adare and Northern Basins, and implies that the crustal structure of the Northern Basin may be more similar to that of the oceanic crust in the Adare Basin than to the stretched continental crust further south in the Ross Sea.

  20. Paleomagnetism of sedimentary cores from the Ross Sea outer shelf and continental slope (PNRA-ROSSLOPE II Project)

    NASA Astrophysics Data System (ADS)

    Macrì, Patrizia; Sagnotti, Leonardo; Caricchi, Chiara; Colizza, Ester

    2016-04-01

    We carried out a paleomagnetic and rock magnetic study of 4 gravity cores sampled in the Ross Sea continental slope of the area to the east of Pennell-Iselin banks. The cores (RS14-C1, C2, C3 and ANTA99-C20) consist of hemipelagic fine-grained (silty-clays) sediments with an IRD component. Rock magnetic and paleomagnetic measurements were carried out at 1-cm spacing on u-channel samples. The data indicate that the cored sediments carry a well-defined characteristic remanent magnetization (ChRM) and have a valuable potential to reconstruct dynamics and amplitude of the geomagnetic field variation at high southern latitudes (ca. 75°S) during the Holocene and the late Pleistocene. The paleomagnetic and rock magnetic data are integrated in a multidisciplinary context which includes previous geological, geophysical, oceanographic and morpho-bathimetric data obtained in the same area in the frame of the PNRA/ROSSLOPE (Past and present sedimentary dynamic in the ROSS Sea: a multidisciplinary approach to study the continental slope) Project. The main aim of the project is to investigate the relation between present and past water mass circulation and to provide a basis for paleoceanographic reconstructions and for the development of a depositional model of the modern processes active along the continental slope.

  1. Continuous and discrete measurements of atmospheric methane from an ice core from Roosevelt Island, East Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Blunier, T.; Simonsen, M. F.; Brook, E.; Lee, J.; Vallelonga, P. T.; Bertler, N. A. N.

    2014-12-01

    A new ice core from Roosevelt Island was drilled for the Roosevelt Island Climate Evolution (RICE) project to establish the history of deglaciation of the Ross Sea. Evidence of glacial retreat in the Ross Sea Embayment shows that deglaciation happened in several stages of rapid collapse and persisted well after the melting of the Northern Hemisphere ice sheets was complete. The drill location on a small island surrounded by sea ice makes dating the core a challenge. We present a timescale for Roosevelt Island using mixing ratios of methane in air preserved within the ice core measured continuously with a Picarro laser spectrometer as well as in high-resolution with gas chromatography (GC). Discrete data from GC analysis over the top 400m of core replicate both the magnitude and variations from other high-resolution ice core records from WAIS Divide, Law Dome, GISP2 and NEEM S1. Both the continuous and discrete methane records of the RICE core were matched to these established records and provide an accurate and consistent depth-age relationship for the past 3.6kyr. The deeper part of the core was measured continuously in July 2014. First inspection of the data suggests that the oldest section of the core reaches into the previous interglacial (Eemian). We will present preliminary evaluated continuous methane data for the deeper part of the core together with a first time scale for the Roosevelt Island ice core.

  2. Thermohaline circulation below the Ross Ice Shelf - A consequence of tidally induced vertical mixing and basal melting

    NASA Technical Reports Server (NTRS)

    Macayeal, D. R.

    1984-01-01

    The warmest water below parts of the Ross Ice Shelf resides in the lowest portion of the water column because of its high salinity. Vertical mixing caused by tidal stirring can thus induce ablation by lifting the warm but dense water into contact with the ice shelf. A numerical tidal simulation indicates that vertically well-mixed conditions predominate in the southeastern part of the sub-ice shelf cavity, where the water column thickness is small. Basal melting in this region is expected to be between 0.05 and 0.5 m/yr and will drive a thermohaline circulation having the following characteristics: high salinity shelf water (at - 1.8 C), formed by winter sea ice production in the open Ross Sea, flows along the seabed toward the tidal mixing fronts below the ice shelf; and meltwater (at -2.2 C), produced in the well-mixed region, flows out of the sub-ice shelf cavity along the ice shelf bottom. Sensitivity of this ablation process to climatic change is expected to be small because high salinity shelf water is constrained to have the sea surface freezing temperature.

  3. [Ross operation using "contegra" conduit in a 5 year old girl with severe aortic valve insufficiency in Kawasaki disease coexisting with infective endocarditis--a case report].

    PubMed

    Piaszczyński, Maciej; Pawelec-Wojtalik, Małgorzata; Orzeszko-Spaczyńska, Anna; Wojtalik, Michał; Siwińska, Aldona; Mrówczyński, Wojciech

    2005-07-01

    A case of a 5-year-old girl with severe dysfunction of aortic valve in Kawasaki disease coexisting with endocarditis, is described. The role of Ross operation in the treatment of this condition is discussed. The 18-months follow-up showed good function of aortic valve and "Contegra" conduit (bovine jugular vein), but long-term follow-up of patients with "Contegra" conduit remains unknown. In conclusion, a Ross operation using "Contegra" conduit in pulmonary position could be effective method in the treatment of dysfunction of aortic valve in Kawasaki disease coexisting with endocarditis in children. PMID:16136434

  4. Recent changes detected on two glaciers at the northern part of James Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Nývlt, Daniel; Kopačková, Veronika; Láska, Kamil; Engel, Zbyněk.

    2010-05-01

    Antarctic Peninsula is one of the regions, which have been exposed to the most rapid warming of the Earth since 1950. Consequences of climate changes are clearly documented by recent disintegration of ice shelves on both sides of the Antarctic Peninsula as well as by the retreat of land-based glaciers. James Ross Island, located close to the northernmost tip of the Antarctic Peninsula, represents an excellent place to study changes in the glacier mass-balance and their sensitivity to a regional warming trend. Two different types of glaciers of the Ulu Peninsula, the Whisky Glacier and the Davies Dome have been studied. Multi-temporal remote sensing data (aerial photographs, Landsat MSS, TM and ETM+ and Aster satellite optical and thermal multispectral data) and field survey allowed detecting changes in extent (2-D) as well as calculating glacier mass-balance changes (3-D) for these two glaciers from 1977 to 2009. The Whisky Glacier is a well-delimited valley glacier located mostly below the local Equilibrium line altitude (ELA). The glacier with high-flow velocities is fed by an intensive snow accumulation caused by prevailing southwestern winds. The Whisky Glacier covers an area of 2.3 km2 and its altitude varies from 215 to 475 m a.s.l. The Davies Dome is a flat-bottom dome glacier. Significant parts of its surface are located above the ELA and limited flow velocities are characteristic for the most parts of its body. However, the Davies Dome has a single 500-700 m wide southwestern outlet flowing towards the Whisky Bay. The Davies Dome extends an area of 6.7 km2 and its altitude ranges from 0 to 514 m a.s.l. Both glaciers experienced massive extension of their ice tongues towards the Brandy Bay during the mid Holocene. Lateral moraines located in front of the both glaciers heading down to the left coast of the Brandy Bay document this event. According to the remote sensing data and field investigations both glaciers have retreated since 1977. Between 2006 and

  5. Physical control of chlorophyll a, POC, and TPN distributions in the pack ice of the Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Arrigo, Kevin R.; Robinson, Dale H.; Dunbar, Robert B.; Leventer, Amy R.; Lizotte, Michael P.

    2003-10-01

    The pack ice ecosystem of the Ross Sea was investigated along a 1470-km north-south transect during the spring 1998 oceanographic program Research on Ocean-Atmosphere Variability and Ecosystem Response in the Ross Sea (ROAVERRS). Snow and sea ice thickness along the transect varied latitudinally, with thinner snow and ice at the northern ice edge and thin new ice in the vicinity of the Ross Sea polynya. Relative to springtime observations in other sea ice regions, algal chlorophyll a (Chl a) concentrations were low. In contrast, particulate organic carbon (POC), total particulate nitrogen (TPN), and POC:Chl a were all high, indicating either that the ice contained substantial amounts of detritus or nonphotosynthetic organisms, or that the algae had a high POC:Chl a ratio. The abundance of Chl a, POC, and TPN in the sea ice was related to ice age and thickness, as well as to snow depth: older ice had thinner snow cover and contained higher algal biomass while new ice in the polynya had lower biomass. Older pack ice was dominated by diatoms (particularly Fragilariopsis cylindrus) and had vertical distributions of Chl a, POC, and TPN that were related to salinity, with higher biomass at the ice-water interface. Fluorescence-based measurements of photosynthetic competence (Fv/Fm) were higher at ice-water interfaces, and photosynthesis-irradiance characteristics measured for bottom ice algae were comparable to those measured in pack ice communities of other regions. Nutrient concentrations in extracted sea ice brines showed depletion of silicate and nitrate, depletion or regeneration of phosphate and nitrite, and production of ammonium when normalized to seawater salinity; however, concentrations of dissolved inorganic nitrogen, phosphorous, and silica were typically above levels likely to limit algal growth. In areas where pack ice and snow cover were thickest, light levels could be limiting to algal photosynthesis. Enrichment of δ13C-POC in the sea ice was correlated

  6. A Reference-Intensive Embedded Librarian Program: Kresge Business Administration Library's Program to Support Action-Based Learning at the Ross School of Business

    ERIC Educational Resources Information Center

    Berdish, Laura; Seeman, Corey

    2010-01-01

    While a great deal of literature on embedded librarians in academic libraries is focused on the role of instructor, there are many other services that could be provided by librarians working closely with students. The Kresge Business Administration Library (Stephen M. Ross School of Business at the University of Michigan) has created a unique…

  7. Do geese fully develop brood patches? A histological analysis of lesser snow geese (Chen caerulescens caerulescens) and Ross's geese (C. rossii)

    USGS Publications Warehouse

    Jonsson, J.E.; Afton, A.D.; Homberger, D.G.; Henk, W.G.; Alisauskas, R.T.

    2006-01-01

    Most birds develop brood patches before incubation; epidermis and dermis in the brood patch region thicken, and the dermal connective tissue becomes increasingly vascularized and infiltrated by leukocytes. However, current dogma states that waterfowl incubate without modifications of skin within the brood patch region. The incubation periods of lesser snow geese (Chen caerulescens caerulescens; hereafter called snow geese) and Ross's geese (C. rossii) are 2-6 days shorter than those of other goose species; only females incubate. Thus, we hypothesized that such short incubation periods would require fully developed brood patches for sufficient heat transfer from incubating parents to eggs. We tested this hypothesis by analyzing the skin histology of abdominal regions of snow and Ross's geese collected at Karrak Lake, Nunavut, Canada. For female snow geese, we found that epidermis and dermis had thickened and vascularization of dermis was 14 times greater, on average, than that observed in males (n=5 pairs). Our results for Ross's geese (n=5 pairs) were more variable, wherein only one of five female Ross's geese fully developed a brood patch. Our results are consistent with three hypotheses about brood patch development and its relationship with different energetic cost-benefit relationships, resulting from differences in embryonic development and body size. ?? Springer-Verlag 2006.

  8. Using C-Span in the Classroom to Enhance Student Analysis of Ross Perot's Sensitivity with American Diversity During the 1992 Presidential Campaign

    ERIC Educational Resources Information Center

    Schnell, James

    2007-01-01

    The C-SPAN application to be described in this article is useful in the Cross-Cultural Communication and Mass Media courses. This application focuses on how we define what connotes sensitivity & insensitivity with diversity issues and how journalistic interpretation can affect our perception via mass media. Businessman Ross Perot rose from…

  9. Royal Society of Tropical Medicine and Hygiene 91st Annual General Meeting at Manson House, London, 18 June 1998. Traveller's tales. Sir Ronald Ross and India.

    PubMed

    Gibson, M E

    1998-01-01

    Brief mention is given of the early life of Sir Ronald Ross and an account of the events which led to his discovery of the method of transmission of malaria parasites. His later association with India is also referred to. PMID:10326099

  10. Using C-Span To Study Ross Perot's Expression of Sensitivity and Insensitivity with Diversity Issues during the 1992 Presidential Campaign.

    ERIC Educational Resources Information Center

    Schnell, Jim

    C-SPAN videotapes provide an innovative database that promises to be a significant benefit to researchers of public figures and issues by allowing researchers to analyze public figures in their own words, without journalistic interpretation. Such analysis was applied to Ross Perot's 1992 campaign in addressing his perceived insensitivity to…

  11. A Critique of Julie L. Ozanne, Natalie Ross Adkins, and Jennifer A. Sandlin's: "Shopping {For} Power: How Adult Literacy Learners Negotiate"

    ERIC Educational Resources Information Center

    Coutinho, Colin

    2008-01-01

    This paper will review the article entitled, "Shopping {For} Power: How Adult Literacy Learners Negotiate" [EJ756994] by authors Julie L. Ozanne, Natalie Ross Adkins, and Jennifer A. Sandlin. The authors argue that functional literacy in the United States is an important issue and needs to play a larger role in adult literacy programs. Their…

  12. Common Core State Standards and Teacher Effectiveness. Q&A with Ross Wiener, Ph.D. REL Mid-Atlantic Teacher Effectiveness Webinar Series

    ERIC Educational Resources Information Center

    Regional Educational Laboratory Mid-Atlantic, 2013

    2013-01-01

    In this REL Mid-Atlantic webinar, Dr. Ross Wiener, Vice President and Executive Director of the Education and Society Program, Aspen Institute, discussed strategies for integrating the Common Core State Standards (CCSS) into teacher effectiveness systems, including ways in which the CCSS can support professional growth and inform teacher…

  13. Amazon River

    Atmospheric Science Data Center

    2013-04-17

    ... the Rio Solimoes and the Rio Negro converge to form the Amazon River. This image from the Multi-angle Imaging SpectroRadiometer (MISR) ... date:  Jul 23, 2000 Images:  Amazon River location:  South America thumbnail:  ...

  14. Mississippi River

    Atmospheric Science Data Center

    2014-05-15

    ... View Larger Image The mighty Mississippi River, from its source at Lake Itasca, Minnesota to the Gulf of Mexico, is ... heavy rainfall on areas traversed by the upper Mississippi River. Each image in this pair covers an identical 195-kilometer x ...

  15. The cryptoendolithic microbial environment in the Ross Desert of Antarctica: satellite-transmitted continuous nanoclimate data, 1984 to 1986

    NASA Technical Reports Server (NTRS)

    Friedmann, E. I.; McKay, C. P.; Nienow, J. A.

    1987-01-01

    A satellite mediated station for monitoring nanoclimate (climate in the millimeter range) data, suitable for use in polar regions is described. The station, located in the Ross desert of Antarctica, has been in operation for more than 3 years, measuring rock temperatures, air temperature, light, snow, wind, and moisture. The data indicate that biological activity in the cryptoendolithic microbial ecosystem is limited to the period from mid November to mid February. The total number of hours of biological activity, based on assumptions of the minimum light, temperature and moisture requirements of the community, is less than 1000 h/year. The time above 0 degrees C, representing more nearly optimal conditions, is between 50 and 550 h/year, depending on the orientation of the surface.

  16. Continuous Nanoclimate Data (1985-1988) from the Ross Desert (McMurdo Dry Valleys) Cryptoendolithic Microbial Ecosystem

    NASA Technical Reports Server (NTRS)

    McKay, Christopher P.; Nienow, James; Meyer, Michael A.; Friedmann, E. Imre

    1993-01-01

    We have collected year-round nanoclimate data for the cryptoendolithic microbial habitat in sandstones of the Ross desert, Antarctica, obtained with an Argos satellite data system. Data for two sites in the McMurdo Dry Valleys are available: Linnaeus Terrace, January 1985 to June 1988, and Battleship Promontory, 1986-1987. The focus of this research is ecological, and hence year-round environmental data have been obtained for the ambient environment as well as for conditions within the rock. Using data from the summer, we compare the conditions inside the rock to the outside weather. This demonstrates how the rock provides a shelter for the endolithic microbial community. The most important property of the rock is that it absorbs the summer sunlight, thereby warming up to temperatures above freezing. This warming allows snowmelt to seep into the rock, and the moisture level in the rocks can remain high for weeks against loss to the dry environment.

  17. Time budgets of Snow Geese Chen caerulescens and Ross's Geese Chen rossii in mixed flocks: Implications of body size, ambient temperature and family associations

    USGS Publications Warehouse

    Jonsson, J.E.; Afton, A.D.

    2009-01-01

    Body size affects foraging and forage intake rates directly via energetic processes and indirectly through interactions with social status and social behaviour. Ambient temperature has a relatively greater effect on the energetics of smaller species, which also generally are more vulnerable to predator attacks than are larger species. We examined variability in an index of intake rates and an index of alertness in Lesser Snow Geese Chen caerulescens caerulescens and Ross's Geese Chen rossii wintering in southwest Louisiana. Specifically we examined variation in these response variables that could be attributed to species, age, family size and ambient temperature. We hypothesized that the smaller Ross's Geese would spend relatively more time feeding, exhibit relatively higher peck rates, spend more time alert or raise their heads up from feeding more frequently, and would respond to declining temperatures by increasing their proportion of time spent feeding. As predicted, we found that Ross's Geese spent more time feeding than did Snow Geese and had slightly higher peck rates than Snow Geese in one of two winters. Ross's Geese spent more time alert than did Snow Geese in one winter, but alert rates differed by family size, independent of species, in contrast to our prediction. In one winter, time spent foraging and walking was inversely related to average daily temperature, but both varied independently of species. Effects of age and family size on time budgets were generally independent of species and in accordance with previous studies. We conclude that body size is a key variable influencing time spent feeding in Ross's Geese, which may require a high time spent feeding at the expense of other activities. ?? 2008 The Authors.

  18. Timing of the Northern Prince Gustav Ice Stream retreat and the deglaciation of northern James Ross Island, Antarctic Peninsula during the last glacial-interglacial transition

    NASA Astrophysics Data System (ADS)

    Nývlt, Daniel; Braucher, Régis; Engel, Zbyněk; Mlčoch, Bedřich

    2014-09-01

    The Northern Prince Gustav Ice Stream located in Prince Gustav Channel, drained the northeastern portion of the Antarctic Peninsula Ice Sheet during the last glacial maximum. Here we present a chronology of its retreat based on in situ produced cosmogenic 10Be from erratic boulders at Cape Lachman, northern James Ross Island. Schmidt hammer testing was adopted to assess the weathering state of erratic boulders in order to better interpret excess cosmogenic 10Be from cumulative periods of pre-exposure or earlier release from the glacier. The weighted mean exposure age of five boulders based on Schmidt hammer data is 12.9 ± 1.2 ka representing the beginning of the deglaciation of lower-lying areas (< 60 m a.s.l.) of the northern James Ross Island, when Northern Prince Gustav Ice Stream split from the remaining James Ross Island ice cover. This age represents the minimum age of the transition from grounded ice stream to floating ice shelf in the middle continental shelf areas of the northern Prince Gustav Channel. The remaining ice cover located at higher elevations of northern James Ross Island retreated during the early Holocene due to gradual decay of terrestrial ice and increase of equilibrium line altitude. Schmidt hammer R-values are inversely correlated with 10Be exposure ages and could be used as a proxy for exposure history of individual granite boulders in this region and favour the hypothesis of earlier release of boulders with excessive 10Be concentrations from glacier directly at this site. These data provide evidences for an earlier deglaciation of northern James Ross Island when compared with other recently presented cosmogenic nuclide based deglaciation chronologies, but this timing coincides with rapid increase of atmospheric temperature in this marginal part of Antarctica.

  19. Seasonal variation of air temperature at the Mendel Station, James Ross Island in the period of 2006-2009

    NASA Astrophysics Data System (ADS)

    Laska, Kamil; Prošek, Pavel; Budík, Ladislav

    2010-05-01

    Key words: air temperature, seasonal variation, James Ross Island, Antarctic Peninsula Recently, significant role of the atmospheric and oceanic circulation variation on positive trend of near surface air temperature along the Antarctic Peninsula has been reported by many authors. However, small number of the permanent meteorological stations located on the Peninsula coast embarrasses a detail analysis. It comprises analysis of spatiotemporal variability of climatic conditions and validation of regional atmospheric climate models. However, geographical location of the Czech Johann Gregor Mendel Station (hereafter Mendel Station) newly established on the northern ice-free part of the James Ross Island provides an opportunity to fill the gap. There are recorded important meteorological characteristics which allow to evaluate specific climatic regime of the region and their impact on the ice-shelf disintegration and glacier retreat. Mendel Station (63°48'S, 57°53'W) is located on marine terrace at the altitude of 7 m. In 2006, a monitoring network of several automatic weather stations was installed at different altitudes ranging from the seashore level up to mesas and tops of glaciers (514 m a.s.l.). In this contribution, a seasonal variation of near surface air temperature at the Mendel Station in the period of 2006-2009 is presented. Annual mean air temperature was -7.2 °C. Seasonal mean temperature ranged from +1.4 °C (December-February) to -17.7 °C (June-August). Frequently, the highest temperature occurred in the second half of January. It reached maximum of +8.1 °C. Sudden changes of atmospheric circulation pattern during winter caused a large interdiurnal variability of air temperature with the amplitude of 30 °C.

  20. Penguin population dynamics over the past 1500 years in response to climate change in the Ross Sea region, East Antarctica

    NASA Astrophysics Data System (ADS)

    Liu, X.; Nie, Y.

    2013-12-01

    Several ornithogenic sediment profiles were collected from lakes and catchments near penguin colonies in the ice-free areas of the Ross Sea region. According to the analysis on elemental and isotopic geochemistry, As, Cd, Cu, P, S, Se and Zn were identified as bio-elements for the input of penguin droppings into the sediments. The 210Pb-137Cs and AMS14C dating results showed the chronology of these determined sediment profiles covered the different time spans from 1500 to 200 cal yr BP. Factor analysis on these bio-elements can be used to reconstruct historical change of penguin population, and the result showed that the penguin population, which was reconstructed from the shorter profiles (younger than 500 years) at Cape Crozier and Beaufort Island of Ross Sea region, displayed clear peaks in the recent decades of years. This finding is in accordance with global warming and modern observation data. The penguin population reconstructed from the longer sediment profiles excavated from Cape Bird showed more fluctuations. Two sediment profiles, collected from the lower terrain of mid Cape Bird, recorded higher penguin density between 1000 and 600 cal. yr BP and then decreased sharply. However, one sediment profile on higher terrain in mid Cape Bird recorded a sudden increase in penguin population from around 600 yr BP. We believed the population peaks recorded in the different sediments profiles was indicative of a migration within the penguin colonies of Cape Bird, from lower terrain to higher terrain. This migration was likely driven by the severe climate fluctuation during the Little Ice Age in the study region. Our results clearly showed the change of penguin ecology can sensitively indicate climate change in the East Antarctica.

  1. Early season depletion of dissolved iron in the Ross Sea polynya: Implications for iron dynamics on the Antarctic continental shelf

    NASA Astrophysics Data System (ADS)

    Sedwick, P. N.; Marsay, C. M.; Sohst, B. M.; Aguilar-Islas, A. M.; Lohan, M. C.; Long, M. C.; Arrigo, K. R.; Dunbar, R. B.; Saito, M. A.; Smith, W. O.; Ditullio, G. R.

    2011-12-01

    The Ross Sea polynya is among the most productive regions in the Southern Ocean and may constitute a significant oceanic CO2 sink. Based on results from several field studies, this region has been considered seasonally iron limited, whereby a "winter reserve" of dissolved iron (dFe) is progressively depleted during the growing season to low concentrations (˜0.1 nM) that limit phytoplankton growth in the austral summer (December-February). Here we report new iron data for the Ross Sea polynya during austral summer 2005-2006 (27 December-22 January) and the following austral spring 2006 (16 November-3 December). The summer 2005-2006 data show generally low dFe concentrations in polynya surface waters (0.10 ± 0.05 nM in upper 40 m, n = 175), consistent with previous observations. Surprisingly, our spring 2006 data reveal similar low surface dFe concentrations in the polynya (0.06 ± 0.04 nM in upper 40 m, n = 69), in association with relatively high rates of primary production (˜170-260 mmol C m-2 d-1). These results indicate that the winter reserve dFe may be consumed relatively early in the growing season, such that polynya surface waters can become "iron limited" as early as November; i.e., the seasonal depletion of dFe is not necessarily gradual. Satellite observations reveal significant biomass accumulation in the polynya during summer 2006-2007, implying significant sources of "new" dFe to surface waters during this period. Possible sources of this new dFe include episodic vertical exchange, lateral advection, aerosol input, and reductive dissolution of particulate iron.

  2. Basal mass budget of Ross and Filchner-Ronne ice shelves, Antarctica, derived from Lagrangian analysis of ICESat altimetry

    NASA Astrophysics Data System (ADS)

    Moholdt, Geir; Padman, Laurie; Fricker, Helen Amanda

    2014-11-01

    Traditional methods of deriving temporal variability of Antarctic ice-shelf elevation from satellite altimetry use a fixed ("Eulerian") reference frame, where the measured changes include advection of ice thickness gradients between measurement epochs. We present a new method which removes advection effects by using an independent velocity field to compare elevations in a moving ("Lagrangian") reference frame. Applying the technique to ICESat laser altimetry for the period 2003-2009 over the two largest Antarctic ice shelves, Ross and Filchner-Ronne, we show that the Lagrangian approach reduces the variability of derived elevation changes by about 50% compared to the Eulerian approach and reveals clearer spatial patterns of elevation change. The method simplifies the process of estimating basal mass budget from the residual of all other processes that contribute to ice-shelf elevation changes. We use field data and ICESat measurements over ice rises and the grounded ice sheet to account for surface accumulation and changes in firn air content, and remove the effect of ice-flow divergence using surface velocity and ice thickness data. The results show highest basal melt rates (>5 m a-1) near the deep grounding lines of major ice streams, but smaller melt rates (<5 m a-1) near the ice-shelf fronts are equally important to total meltwater production since they occur over larger areas. Integrating over the entire ice-shelf areas, we obtain basal mass budgets of -50 ± 64 Gt a-1 for Ross and -124 ± 66 Gt a-1 for Filchner-Ronne, with changes in firn air content as the largest error source.

  3. Plio-Quaternary seismic stratigraphy of Ross Sea eastern basin (Antarctica): Implications to glacial history and basin evolution

    SciTech Connect

    Alonso, M.B.; Diaz, J.I. ); Anderson, J.S.; Bartek, L. )

    1991-03-01

    From air-gun and water-gun high-resolution single-channel seismic records, seven seismic units are defined, overlying the Ross Sea Unconformity, in the Plio-Quaternary sequences of the Ross Sea Eastern basin. These units are up to 600 m in thickness and generally thin onshore, disappearing near the western limit of the basin. The units are separated by smooth erosional surfaces characterized by continuous, high-amplitude reflectors. By correlation to DSDP Site 272, seismic units I and II are Pliocene in age, and the overlying units (III or VII) are Quaternary in age. Units I, III, and VII are basinal in extension and the others are confined to the central part of the basin. Thickness of the units ranges from 50 to 120 m, and they are mainly characterized by lenticular and wedge geometrics. Three acoustic facies are discerned: stratified, semitransparent, and chaotic. Wide (7 km) lenticular deposits, containing chaotic facies, are incised by U-shaped channels in seismic units, II, III (both up to 0.5 km wide), and VI (2 km wide), The spatial distribution of these channels indicates a paleodrainage system in which ice streams followed flow paths similar to those of the present. The major geological events that occurred on the continental shelf during Plio-Quaternary time were: (1) the first channel incisions are identified near the boundary of the late Pliocene-Quaternary; (2) the advance and retreat of the ice sheet resulted in widespread erosion processes alternating with deposition of glacial and glaciomarine sediments; (3) the largest depocenter has been always situated in the shelf break environment, near the western limit of the basin; and (4) the only important progradation of the shelf occurred during the late Pliocene, and since then the shelf has been aggradational.

  4. River Times.

    ERIC Educational Resources Information Center

    Auldridge, Teresa; And Others

    The James River is one of the most precious resources of Virginia. It was the site of the first permanent English settlement in the New World; the power of the water at the Fall Zone was a major factor in the development of Richmond; and the river served as a primary transportation route to the West via the Kanawha Canal. Both the water itself and…

  5. P and S velocity structure of the upper mantle beneath the Transantarctic Mountains, East Antarctic craton, and Ross Sea from travel time tomography

    NASA Astrophysics Data System (ADS)

    Watson, Timothy; Nyblade, Andrew; Wiens, Douglas A.; Anandakrishnan, Sridhar; Benoit, Margaret; Shore, Patrick J.; Voigt, Donald; Vandecar, John

    2006-07-01

    P and S wave travel times from teleseismic earthquakes recorded by the Transantarctic Mountains Seismic Experiment (TAMSEIS) have been used to tomographically image upper mantle structure beneath portions of the Transantarctic Mountains (TAM), the East Antarctic (EA) craton, and the West Antarctic rift system (WARS) in the vicinity of Ross Island, Antarctica. The TAM form a major tectonic boundary that divides the stable EA craton and the tectonically active WARS. Relative arrival times were determined using a multichannel cross-correlation technique on teleseismic P and S phases from earthquakes with mb ≥ 5.5. 3934 P waves were used from 322 events, and 2244 S waves were used from 168 events. Relative travel time residuals were inverted for upper mantle structure using VanDecar's method. The P wave tomography model reveals a low-velocity anomaly in the upper mantle of approximately δVp = -1 to -1.5% in the vicinity of Ross Island extending laterally 50 to 100 km beneath the TAM from the coast, placing the contact between regions of fast and slow velocities well inland from the coast beneath the TAM. The magnitude of the low-velocity anomaly in the P wave model appears to diminish beneath the TAM to the north and south of Ross Island. The depth extent of the low-velocity anomaly is not well constrained, but it probably is confined to depths above ˜200 km. The S wave model, within resolution limits, is consistent with the P wave model. The low-velocity anomaly within the upper mantle can be attributed to a 200-300 K thermal anomaly, consistent with estimates obtained from seismic attenuation measurements. The presence of a thermal anomaly of this magnitude supports models invoking a thermal buoyancy contribution to flexurally driven TAM uplift, at least in the Ross Island region of the TAM. Because the magnitude of the anomaly to the north and south of Ross Island may diminish, the thermal contribution to the uplift of the TAM could be variable along strike

  6. ANDRILL Targets Coulman High, Ross Sea, Antarctica, to Recover Early History of the West Antarctic Ice Sheet

    NASA Astrophysics Data System (ADS)

    Levy, Richard; Luyendyk, Bruce; Rack, Frank; Wilson, Doug; Sorlien, Chris; Fischbein, Steve; Harwood, David; Pyne, Alex; Falconer, Tamsin; Science Committee, Andrill

    2010-05-01

    The international Antarctic Geological Drilling (ANDRILL) Program recently recovered long (> 1000 m) rock and sediment cores from two sites in McMurdo Sound, and now aims to recover new stratigraphic sections from sites beneath the Ross Ice Shelf east of Ross Island on the structural Coulman High. ANDRILL will utilize new drilling capabilities to operate from a fast moving ice shelf platform (~700 m/year northward) and complete two deep holes. The drilling target for the Coulman High Project is a Cretaceous (?) to lower Miocene section. Recovery of these strata will allow our team to investigate: (1) the behaviour of ice sheets in West Antarctica during periods of moderate to high greenhouse gas levels; (2) the Antarctic environment in warm greenhouse periods; and (3) tectonic processes within the West Antarctic Rift System. In 2003 and 2004 a marine multichannel seismic grid was completed across Coulman High as close as 500 m from the front of the Ross Ice Shelf. The ice shelf has advanced 4 km north and now sits over several seismic lines providing a platform from which to drill into sites located on those lines. Selected drill sites target ~600 m of laterally continuous sediments underlain by a major regional unconformity and 350 - 850 m of faulted sediments and basement beneath it. Seismic correlation from Deep Sea Drilling Project Sites 272 and 273 to the Coulman High sites implies that the section proposed to be drilled predates 19 Ma. Several new operational challenges exist at the Coulman High sites and work is underway to modify existing technology and develop new approaches to address them. Access to the sea-floor requires melting through 250 meters of ice shelf using the ANDRILL hot water drill, which has previously be used to maintain an open hole through 80 meters of ice. The amount of lateral deflection that ANDRILL's sea-riser can accommodate is limited by water column thickness (630 m) and amount of ice shelf movement of ~2 m/day. These parameters

  7. The Ross Orogen and Lachlan Fold Belt in Marie Byrd Land, Northern Victoria Land and New Zealand: implication for the tectonic setting of the Lachlan Fold Belt in Antarctica

    USGS Publications Warehouse

    Bradshaw, J.D.

    2007-01-01

    Correlation of the Cambrian Delamerian Orogen of Australia and Ross Orogen of the Transantarctic Mountains widely accepted but the extension of the adjacent Lachlan Orogen into Antarctica is controversial. Outside the main Ross-Delamerian belt, evidence of this orogeny is preserved at Mt Murphy in Marie Byrd Land and the in Takaka Terrane of New Zealand. In all pre-break- configurations of the SW Pacific, these two areas are far removed from the Ross-Delamerian belt. Evidence from conglomerates in the Takaka Terrane, however, shows that in Late Cambrian times it was adjacent to the Ross Orogen. This indicates major tectonic displacements within Gondwana after the Cambrian and before break-up. The Lachlan Orogen formed in an extensional belt in a supra-subduction zone setting and the Cambrian rocks of Marie Byrd Land and New Zealand are interpreted as parts of a rifted continental ribbon on the outboard side of the Lachlan belt.

  8. Spatial analysis of trends in primary production and relationship with large-scale climate variability in the Ross Sea, Antarctica (1997-2013)

    NASA Astrophysics Data System (ADS)

    Schine, Casey M. S.; van Dijken, Gert; Arrigo, Kevin R.

    2016-01-01

    Recent studies have documented an increase in sea ice extent and the duration of the ice season in the Ross Sea, Antarctica. We conducted a satellite-based study to quantify changes in net primary production (NPP) and chlorophyll a (Chl a) in response to the observed changes in ice dynamics in the Ross Sea south of 60°S. Our study covers a 16 year time period (1997-2013) and incorporates both the shelf and off-shelf regions of the Ross Sea. We observed significant secular changes in NPP from 1997 to 2013 in the off-shelf region, with NPP increasing on the eastern side and decreasing on the western side of our study area. The changes we observed in NPP are consistent with the changes we observed in sea surface temperature (SST) and open water days (OWDs), decreasing (increasing) on the western (eastern) side of our study area. Finally, we examined the influence of the Southern Annular Mode (SAM) and the El Niño Southern Oscillation (ENSO), on SST, OWDs, Chl a, and NPP in the Ross Sea and observed a significant relationship between the state of the SAM and ENSO and SST, OWDs, and NPP across the study region. The response of OWDs, SST, and NPP to atmospheric forcing by SAM and ENSO was opposite for the shelf and off-shelf regions, such that during a positive phase of SAM or negative phase of ENSO (La Niña), SST, OWDs, and NPP increased on the shelf and decreased in the off-shelf region.

  9. Neonatal Ross-Konno operation and endocardial fibroelastosis resection after foetal percutaneous aortic valve balloon valvuloplasty: a complex approach to rescue the left heart.

    PubMed

    Perez-Negueruela, Carolina; Mayol, Javier; Prada, Fredy; Caffarena-Calvar, Jose Maria

    2014-09-01

    We report a case of a patient who presented with aortic stenosis and a borderline left ventricle during foetal life. A balloon aortic valve valvuloplasty was performed in uterus, and in the postnatal period for relief of the left ventricular outflow tract obstruction followed by a Ross-Konno procedure with fibroelastosis resection. These successful interventions allowed left ventricular growth and the conversion to a biventricular circulation after a single-stage surgery. PMID:24627438

  10. Intra-seasonal variation in foraging behavior among Adélie penguins (Pygocelis adeliae) breeding at Cape Hallett, Ross Sea, Antarctica

    USGS Publications Warehouse

    Lyver, P.O.B.; MacLeod, C.J.; Ballard, G.; Karl, B.J.; Barton, K.J.; Adams, J.; Ainley, D.G.; Wilson, P.R.

    2011-01-01

    We investigated intra-seasonal variation in foraging behavior of chick-rearing Adélie penguins, Pygoscelis adeliae, during two consecutive summers at Cape Hallett, northwestern Ross Sea. Although foraging behavior of this species has been extensively studied throughout the broad continental shelf region of the Ross Sea, this is the first study to report foraging behaviors and habitat affiliations among birds occupying continental slope waters. Continental slope habitat supports the greatest abundances of this species throughout its range, but we lack information about how intra-specific competition for prey might affect foraging and at-sea distribution and how these attributes compare with previous Ross Sea studies. Foraging trips increased in both distance and duration as breeding advanced from guard to crèche stage, but foraging dive depth, dive rates, and vertical dive distances travelled per hour decreased. Consistent with previous studies within slope habitats elsewhere in Antarctic waters, Antarctic krill (Euphausia superba) dominated chick meal composition, but fish increased four-fold from guard to crèche stages. Foraging-, focal-, and core areas all doubled during the crèche stage as individuals shifted distribution in a southeasterly direction away from the coast while simultaneously becoming more widely dispersed (i.e., less spatial overlap among individuals). Intra-specific competition for prey among Adélie penguins appears to influence foraging behavior of this species, even in food webs dominated by Antarctic krill.

  11. Intra-seasonal variation in foraging behavior among Adélie penguins (Pygocelis adeliae) breeding at Cape Hallett, Ross Sea, Antarctica

    USGS Publications Warehouse

    Lyver, P.O.B.; MacLeod, C.J.; Ballard, G.; Karl, B.J.; Barton, K.J.; Adams, J.; Ainley, D.G.; Wilson, P.R.

    2011-01-01

    We investigated intra-seasonal variation in foraging behavior of chick-rearing Adélie penguins,Pygoscelis adeliae, during two consecutive summers at Cape Hallett, northwestern Ross Sea. Although foraging behavior of this species has been extensively studied throughout the broad continental shelf region of the Ross Sea, this is the first study to report foraging behaviors and habitat affiliations among birds occupying continental slope waters. Continental slope habitat supports the greatest abundances of this species throughout its range, but we lack information about how intra-specific competition for prey might affect foraging and at-sea distribution and how these attributes compare with previous Ross Sea studies. Foraging trips increased in both distance and duration as breeding advanced from guard to crèche stage, but foraging dive depth, dive rates, and vertical dive distances travelled per hour decreased. Consistent with previous studies within slope habitats elsewhere in Antarctic waters, Antarctic krill (Euphausia superba) dominated chick meal composition, but fish increased four-fold from guard to crèche stages. Foraging-, focal-, and core areas all doubled during the crèche stage as individuals shifted distribution in a southeasterly direction away from the coast while simultaneously becoming more widely dispersed (i.e., less spatial overlap among individuals). Intra-specific competition for prey among Adélie penguins appears to influence foraging behavior of this species, even in food webs dominated by Antarctic krill.

  12. New relative sea-level curves for the southern Scott Coast, Antarctica: evidence for Holocene deglaciation of the western Ross Sea

    NASA Astrophysics Data System (ADS)

    Hall, Brenda L.; Denton, George H.

    1999-12-01

    Here we present new relative sea-level (RSL) curves developed from Holocene-aged raised beaches along the southern Scott Coast of the western Ross Sea, Antarctica. Fifty-four dates of marine shells, seal skin and elephant seal remains incorporated within raised beaches during storms afford a chronology for these curves. All of the curves show the same pattern and timing of RSL change within a small range of error. The best-dated curve suggests that final unloading of grounded Ross Sea ice from the southern Scott Coast and McMurdo Sound region occurred shortly before 6500 14C yr BP. This age is consistent with glacial geological evidence that places deglaciation between 5730 and 8340 14C yr BP. Our data strongly suggest that grounding-line retreat of the Ross Sea ice sheet southward through the McMurdo Sound region occurred in mid- and late Holocene time. If this is correct, then rising sea level could not have driven ice recession to the present-day grounding line on the Siple Coast, because global deglacial sea-level rise was essentially accomplished by mid-Holocene time.

  13. Microbial fossil record of rocks from the Ross Desert, Antarctica: implications in the search for past life on Mars

    NASA Astrophysics Data System (ADS)

    Wierzchos, Jacek; Ascaso, Carmen

    2002-01-01

    Cryptoendolithic microbial communities living within Antarctic rocks are an example of survival in an extremely cold and dry environment. The extinction of these micro-organisms formerly colonizing sandstone in the Mount Fleming area (Ross Desert), was probably provoked by the hostile environment. This is considered to be a good terrestrial analogue of the first stage of the disappearance of possible life on early Mars. To date, only macroscopically observed indirect biomarkers of the past activity of cryptoendoliths in Antarctic rocks have been described. The present paper confirms, for the first time, the existence of cryptoendolith microbial fossils within these sandstone rocks. The novel in situ application of scanning electron microscopy with backscattered electron imaging and simultaneous use of X-ray energy dispersive spectroscopy allowed the clear detection of microfossils left behind by Antarctic endoliths. Careful interpretation of the morphological features of cells, such as preserved cell walls in algae, fungi and bacteria, cytoplasm elements such as chloroplast membranes in algae and organic matter traces, mineral associations, and the spatial context of these structures all point to their identification as cryptoendolith microfossils. This type of investigation will prompt the development of research strategies aimed at locating and identifying the signs that Martian microbiota, probably only bacteria if they existed, may have been left for us to see.

  14. Distribution patterns and possible influencing factors of As speciation in ornithogenic sediments from the Ross Sea region, East Antarctica.

    PubMed

    Lou, Chuangneng; Liu, Xiaodong; Liu, Wenqi; Wu, Libin; Nie, Yaguang; Emslie, Steven D

    2016-05-15

    Ornithogenic sediments are rich in toxic As (arsenic) compounds, posing a potential threat to local ecosystems. Here we analyzed the distribution of As speciation in three ornithogenic sediment profiles (MB6, BI and CC) collected from the Ross Sea region, East Antarctica. The distributions of total As and total P (phosphorus) concentrations were highly consistent in all three profiles, indicating that guano input is a major factor controlling total As distribution in the ornithogenic sediments. The As found in MB6 and CC is principally As(V) (arsenate), in BI As(III) (arsenite) predominates, but the As in fresh guano is largely composed of DMA (dimethylarsinate). The significant difference of As species between fresh guano and ornithogenic sediment samples may be related to diagenetic processes after deposition by seabirds. Based on analysis of the sedimentary environment in the studied sediments, we found that the redox conditions have an obvious influence on the As speciation distribution. Moreover, the distributions of As(III) and chlorophyll a in the MB6 and BI profiles are highly consistent, demonstrating that aquatic algae abundance may also influence the distribution patterns of As speciation in the ornithogenic sediments. PMID:26930318

  15. Glacial-interglacial sea ice proxies from the Antarctic Peninsula using the James Ross Island ice core.

    NASA Astrophysics Data System (ADS)

    Benton, A. K.; Mulvaney, R.; Triest, J.; Abram, N.

    2014-12-01

    Ice core records from Antarctica have shown promise as highly-resolved indicators of regional sea ice change, but to date semi-quantified reconstructions do not extend back more than ~150 years. In this study the chemical composition of the James Ross Island ice core is presented as a potential sea ice proxy record spanning the full Holocene and into the last glacial interval. A CFA-TE method was used to analyse the chemical composition of the entire 363.9m core including final 5m which contains evidence of glacial age ice. MSA- and major anions were measured at 4cm effective resolution, along with trace elements Na, Ca, K, Mg, Mn, H2O2, NO3, total conductivity and dust at <0.5cm effective resolution. Seasonal signals from H2O2 in the upper 50m of the core support the use of non sea salt-SO42- for determining seasonality in deeper sections. This multi-proxy analysis of the oldest ice core to date from the Antarctic Peninsula region allows the concurrent interpretation of sea ice changes and their environmental drivers. The potential dual influence of previous winter sea ice extent and air pathway source region on MSA concentrations in the core are interpreted with use of Na as a winter maximum indicator and Ca and dust signal strength showing changes in dust flux indicating potential source region variation.

  16. Short-term under-ice variability of prokaryotic plankton communities in coastal Antarctic waters (Cape Hallett, Ross Sea)

    NASA Astrophysics Data System (ADS)

    Celussi, Mauro; Paoli, Alessandro; Crevatin, Erica; Bergamasco, Andrea; Margiotta, Francesca; Saggiomo, Vincenzo; Umani, Serena Fonda; Del Negro, Paola

    2009-03-01

    During the 2006 Italian Antarctic expedition a diel sampling was performed close to Cape Hallett (Ross Sea) during the Austral summer. Under-ice seawater samples (˜4 m) were collected every 2 h for 28 h in order to estimate prokaryotic processes' variability and community structure dynamics. Prokaryotic and viral abundances, exoenzymatic activities (β-glucosidase, chitinase, lipase, alkaline phosphatase and leucine aminopeptidase), prokaryotic carbon production ( 3H-leucine incorporation) and community structure (Denaturing Gradient Gel Electrophoresis - DGGE fingerprints) were analysed. Results showed that the diel variability of the prokaryotic activity followed a variation in salinity, probably as a consequence of the periodical thawing of sea ice (driven by solar radiation and air temperature cycles), while negligible variation in viral and prokaryotic abundances occurred. The Bacterial and Archaeal community structures underwent an Operational Taxonomic Units (OTUs) temporal shift from the beginning to the end of the sampling, while Flavobacteria-specific primers highlighted high variations in this group possibly related to sea ice melting and substrate release.

  17. Recent sediment remolding on a deep shelf, Ross Sea: implications for radiocarbon dating of Antarctic marine sediments

    NASA Astrophysics Data System (ADS)

    Domack, Eugene W.; Taviani, Marco; Rodriguez, Anthonio

    1999-11-01

    Coarse, bioclastic rich sands have been widely reported from the banks of the Antarctic continental shelf but their origin is still poorly known. We report on a suite of coarse sediments recovered from the top of the Mawson Bank in the northwestern Ross Sea. Radiocarbon ages of biogenic calcite, for modern and apparently late Pleistocene deposits, range from 1085±45 to 20,895±250 yr B.P.. Discovery of soft tissue (Ascidian) preserved as an incrustation on a pebble at 2 m depth indicates aggregation of the sediment within several months or a year of core recovery. Radiocarbon ages of acid insoluble organic matter (aiom) are less than those of the foraminifera calcite. The aiom ages are also reversed in sequence, indicating reworking of the sediment during deposition. These observations and a review of recently published literature suggest that much of the bank top sediment in Antarctica is presently undergoing remobilization, under the influence of strong currents and/or icebergs even under interglacical (high-stand) sea levels. These observations point out the need for careful, integrated studies on high latitude marine sediment cores before resultant "ages" alone are used as the foundation for paleoglacial reconstructions.

  18. New 3-D view of a middle-shelf grounding-zone wedge in Eastern Basin Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Bart, P. J.; Tomkin, J.

    2008-12-01

    A new large-area multibeam survey of a previously identified grounding zone wedge on the central Ross Sea middle continental shelf was acquired during NBP0802 and NBP0803 in February 2008. Within a regional framework, this wedge corresponds to the third grounding event since the WAIS began the post-LGM retreat. The survey reveals the 3-D detailed view of a lineated topset with iceberg gouges, a smooth multi-lobed foreset and distinct downdip pinchout of the grounding zone wedge. Beyond the down-dip pinchout, older subglacial lineations, oblique to the younger lineations, are evident. The multibeam survey along with sub- bottom profiler records permitted us to precisely position piston cores for each of these morphologic sectors. The combined data may serve as a proxy for evaluating some aspects of the WAIS's modern grounding- zone system. For example, sediment cores at the wedge's thin landward and basinward limits obtained homogenous gray mud below a thin olive-green pelagic drape. The absence of a similar pelagic drape embedded in the homogenous gray muds suggests that grounded ice did not retreat past this location before the WAIS occupied the middle-shelf grounding position. In other words, the pause in WAIS retreat was not associated with any significant re-advance.

  19. Validation of the Antarctic Snow Accumulation and Ice Discharge Basal Stress Boundary in the South Eastern Region of the Ross Ice Shelf, Antarctica

    NASA Astrophysics Data System (ADS)

    Nelson, C. B.; King, K.

    2015-12-01

    The largest ice shelf in Antarctic, Ross Ice Shelf, was investigated over the years of (1970-2015). Near the basal stress boundary between the ice shelf and the West Antarctic ice sheet, ice velocity ranges from a few meters per year to several hundred meters per year in ice streams. Most of the drainage from West Antarctica into the Ross Ice Shelf flows down two major ice streams, each of which discharges more than 20 km3 of ice each year. Along with velocity changes, the warmest water below parts of the Ross Ice Shelf resides in the lowest portion of the water column because of its high salinity. Vertical mixing caused by tidal stirring can thus induce ablation by lifting the warm water into contact with the ice shelf. This process can cause melting over a period of time and eventually cause breakup of ice shelf. With changes occurring over many years a validation is needed for the Antarctic Snow Accumulation and Ice Discharge (ASAID) basal stress boundary created in 2003. After the 2002 Larsen B Ice Shelf disintegration, nearby glaciers in the Antarctic Peninsula accelerated up to eight times their original speed over the next 18 months. Similar losses of ice tongues in Greenland have caused speed-ups of two to three times the flow rates in just one year. Rapid changes occurring in regions surrounding Antarctica are causing concern in the polar science community to research changes occurring in coastal zones over time. During the research, the team completed study on the Ross Ice Shelf located on the south western coast of the Antarctic. The study included a validation of the ABSB vs. the natural basal stress boundary (NBSB) along the Ross Ice Shelf. The ASAID BSB was created in 2003 by a team of researchers headed by National Aeronautics and Space Administration Goddard Space Flight Center (NASA GSFC), with an aim of studying coastal deviations as it pertains to the mass balance of the entire continent. The point data file was aimed at creating a replica of the

  20. High-resolution biogeochemical investigation of the Ross Sea, Antarctica, during the AESOPS (U. S. JGOFS) Program

    NASA Astrophysics Data System (ADS)

    Hales, Burke; Takahashi, Taro

    2004-09-01

    The results of high-resolution biogeochemical measurements in the upper 200 m of the Ross Sea, Antarctica, obtained during the AESOPS (U. S. JGOFS) program using the Lamont Pumping SeaSoar (LPS) are presented. They consist of three west-east transects from 170°E to 180° longitude along the AESOPS study line at 76.5°S and three short north-south transects in the Ross Sea polynya during the initial and maturing stages of phytoplankton blooms in the austral spring and early summer of 1997. The LPS carried an in situ instrument array for measurement of temperature, salinity, fluorescence, photosynthetically active radiation (PAR), and dissolved oxygen. In addition, a high-pressure pump mounted aboard the LPS fish delivered a continuous seawater sample stream to the shipboard laboratory for high-speed analysis of its nutrient (nitrate plus nitrate, phosphate, and silicate) and total CO2 concentrations and CO2 partial pressure (PCO2). Vertical resolution of this sampling equaled or exceeded that of hydrostation-style conductivity-temperature-depth (CTD) casts; horizontal resolution (nominally equal to a vertical cast every 3-5 km) exceeded station resolution by a factor of 10. While not perfectly synoptic, the 20-hour duration of these transects is far shorter than the time typically taken to complete the line with conventional sampling methods. These surveys clearly identified three distinct deep water masses below about 100 m: High-Salinity Shelf Water (HSSW) in the western end of the transects, Modified Circumpolar Deep Water (MCDW) in the middle of the transects, and Low-Salinity Shelf Water (LSSW) to the east. The regions to the west were characterized by high biological productivity with high N:P and C:P uptake ratios, but little Si uptake, indicating that the production was dominated by Phaeocystis. To the east, biological productivity was lower than in the west, and low N:P and C:P uptake ratios and high Si uptake indicated the dominance of diatoms. The

  1. Coastal-Change and Glaciological Map of the Northern Ross Ice Shelf Area, Antarctica: 1962-2004

    USGS Publications Warehouse

    Ferrigno, Jane G.; Foley, Kevin M.; Swithinbank, Charles; Williams, Richard S., Jr.

    2007-01-01

    Changes in the area and volume of polar ice sheets are intricately linked to changes in global climate, and the resulting changes in sea level could severely impact the densely populated coastal regions on Earth. Melting of the West Antarctic part alone of the Antarctic ice sheet would cause a sea-level rise of approximately 6 meters (m). The potential sea-level rise after melting of the entire Antarctic ice sheet is estimated to be 65 m (Lythe and others, 2001) to 73 m (Williams and Hall, 1993). The mass balance (the net volumetric gain or loss) of the Antarctic ice sheet is highly complex, responding differently to different conditions in each region (Vaughan, 2005). In a review paper, Rignot and Thomas (2002) concluded that the West Antarctic ice sheet is probably becoming thinner overall; although it is thickening in the west, it is thinning in the north. Thomas and others (2004), on the basis of aircraft and satellite laser altimetry surveys, believe the thinning may be accelerating. Joughin and Tulaczyk (2002), on the basis of analysis of ice-flow velocities derived from synthetic aperture radar, concluded that most of the Ross ice streams (ice streams on the east side of the Ross Ice Shelf) have a positive mass balance, whereas Rignot and others (2004) infer even larger negative mass balance for glaciers flowing northward into the Amundsen Sea, a trend suggested by Swithinbank and others (2003a,b; 2004). The mass balance of the East Antarctic ice sheet is thought by Davis and others (2005) to be strongly positive on the basis of the change in satellite altimetry measurements made between 1992 and 2003. Measurement of changes in area and mass balance of the Antarctic ice sheet was given a very high priority in recommendations by the Polar Research Board of the National Research Council (1986), in subsequent recommendations by the Scientific Committee on Antarctic Research (SCAR) (1989, 1993), and by the National Science Foundation?s (1990) Division of Polar

  2. The sea ice dynamics of Terra Nova Bay and Ross Ice Shelf Polynyas during a spring and winter simulation

    NASA Astrophysics Data System (ADS)

    Petrelli, P.; Bindoff, N. L.; Bergamasco, A.

    2008-09-01

    The Terra Nova Bay (TNB) and Ross Ice Shelf (RIS) polynyas are simulated using a coupled atmosphere-sea ice model in winter 2002 and summer 2000. The atmospheric component of the model is compared with Automatic Weather Stations (AWS) data and shows a significantly increased skill over the ECMWF atmospheric variables. During winter, the sea ice production in TNB is largely determined by katabatic winds. We estimate the monthly production rate to be 8.7 km3/month of sea ice during winter. In early summer (November), the katabatics are weaker and the sea ice production is more influenced by the synoptic wind. The net sea ice production is weaker during November at 1.2 km3/month. The summer production is characterized by a diurnal cycle of melt and sea ice formation. For small coastal polynyas, like TNB, it is important to resolve all the glacier valleys accurately. Increasing the model resolution by a factor of five leads to a doubling of the sea ice formation during winter simulations due to the point intensity of the katabatics winds. For open coastal polynyas, like RIS polynya, sea ice production is largely controlled by synoptic winds and resolution is less important. The RIS polynya production is 61.3 km3 during winter and 19.1 km3 during November. These results are comparable to RIS polynya observations. Although the TNB polynya has a smaller winter sea ice production, the sea ice rate of growth per unit area is 1.6 times that of the RIS polynya.

  3. Subglacial hydrology indicates a major shift in dynamics of the West Antarctic Ross Ice Streams within the next two centuries

    NASA Astrophysics Data System (ADS)

    Goeller, S.; Helm, V.; Thoma, M.; Grosfeld, K.

    2015-07-01

    The mass export of the West Antarctic Ice Sheet (WAIS) is dominated by fast flowing ice streams. Understanding their dynamics is a key to estimate the future integrity of the WAIS and its contributions to global sea level rise. This study focuses on the Ross Ice Streams (RIS) at the Siple Coast. In this sector, observations reveal a high variability of ice stream pathways and velocities which is assumed to be driven by subglacial hydrology. We compute subglacial water pathways for the present-day ice sheet and verify this assumption by finding high correlations between areas of enhanced basal water flow and the locations of the RIS. Moreover, we reveal that the ice flow velocities of the individual ice streams are correlated with the sizes of the water catchment areas draining underneath. The future development of the subglacial hydraulic environment is estimated by applying ice surface elevation change rates observed by ICESat and CryoSat-2 to the present-day ice sheet geometry and thus assessing prognostic basal pressure conditions. Our simulations consistently indicate that a major hydraulic tributary of the Kamb and Whillans Ice Stream (KIS and WIS) will be redirected underneath the Bindschadler Ice Stream (BIS) within the next two centuries. The water catchment area feeding underneath the BIS is estimated to grow by about 50 % while the lower part of the stagnated KIS becomes increasingly separated from its upper hydraulic tributaries. We conclude, that this might be a continuation of the subglacial hydraulic processes which caused the past stagnation of the KIS. The simulated hydraulic rerouting is also capable to explain the observed deceleration of the WIS and indicates a possible future acceleration of the BIS accompanied by an increased ice drainage of the corresponding ice sheet interior.

  4. Summer Epiphytic Diatoms from Terra Nova Bay and Cape Evans (Ross Sea, Antarctica) - A Synthesis and Final Conclusions

    PubMed Central

    Majewska, Roksana; Convey, Peter; De Stefano, Mario

    2016-01-01

    Despite recent advances in polar marine biology and related fields, many aspects of the ecological interactions that are crucial for the functioning of Antarctic shallow water habitats remain poorly understood. Although epiphytic diatoms play an essential role in the Antarctic marine food web, basic information regarding their ecology, biodiversity and biogeography is largely unavailable. Here, we synthesise studies on Ross Sea epiphytic diatoms collected during 11 summer Antarctic expeditions between the years 1989/90 and 2011/12, presenting a full list of diatom taxa associated with three macroalgal species (Iridaea cordata, Phyllophora antarctica, and Plocamium cartilagineum) and their epiphytic sessile fauna. Diatom communities found during the three summer months at various depths and sampling stations differed significantly in terms of species composition, growth form structure and abundances. Densities ranged from 21 to >8000 cells mm-2, and were significantly higher on the surface of epiphytic micro-fauna than on any of the macroalgal species examined. Generally, host organisms characterized by higher morphological heterogeneity (sessile microfauna, ramified Plocamium) supported richer diatom communities than those with more uniform surfaces (Iridaea). Differences between epiphytic communities associated with different macroalgae were reflected better in species composition than in growth form structure. The latter changed significantly with season, which was related strongly to the changing ice conditions. A general trend towards an increasing number of erect forms in deeper waters and tube-dwelling diatoms in the shallowest sites (2–5 m) was also observed. This study explores further important and largely previously unknown aspects of relationships and interactions between Antarctic epiphytic diatoms and their micro- and macro-environments. PMID:27078637

  5. Summer Epiphytic Diatoms from Terra Nova Bay and Cape Evans (Ross Sea, Antarctica)--A Synthesis and Final Conclusions.

    PubMed

    Majewska, Roksana; Convey, Peter; De Stefano, Mario

    2016-01-01

    Despite recent advances in polar marine biology and related fields, many aspects of the ecological interactions that are crucial for the functioning of Antarctic shallow water habitats remain poorly understood. Although epiphytic diatoms play an essential role in the Antarctic marine food web, basic information regarding their ecology, biodiversity and biogeography is largely unavailable. Here, we synthesise studies on Ross Sea epiphytic diatoms collected during 11 summer Antarctic expeditions between the years 1989/90 and 2011/12, presenting a full list of diatom taxa associated with three macroalgal species (Iridaea cordata, Phyllophora antarctica, and Plocamium cartilagineum) and their epiphytic sessile fauna. Diatom communities found during the three summer months at various depths and sampling stations differed significantly in terms of species composition, growth form structure and abundances. Densities ranged from 21 to >8000 cells mm-2, and were significantly higher on the surface of epiphytic micro-fauna than on any of the macroalgal species examined. Generally, host organisms characterized by higher morphological heterogeneity (sessile microfauna, ramified Plocamium) supported richer diatom communities than those with more uniform surfaces (Iridaea). Differences between epiphytic communities associated with different macroalgae were reflected better in species composition than in growth form structure. The latter changed significantly with season, which was related strongly to the changing ice conditions. A general trend towards an increasing number of erect forms in deeper waters and tube-dwelling diatoms in the shallowest sites (2-5 m) was also observed. This study explores further important and largely previously unknown aspects of relationships and interactions between Antarctic epiphytic diatoms and their micro- and macro-environments. PMID:27078637

  6. Analysis of erythemally effective UV radiation at the Mendel Station, James Ross Island in the period of 2006-2007

    NASA Astrophysics Data System (ADS)

    Laska, K.; Prosek, P.; Budik, L.; Budikova, M.

    2009-04-01

    The results of global solar and erythemally effective ultraviolet (EUV) radiation measurements are presented. The radiation data were collected within the period of 2006-2007 at the Czech Antarctic station J. G. Mendel, James Ross Island (63°48'S, 57°53'W). Global solar radiation was measured by a Kipp&Zonen CM11 pyranometer. EUV radiation was measured according to the McKinley and Diffey Erythemal Action Spectrum with a Solar Light broadband UV-Biometer Model 501A. The effects of stratospheric ozone concentration and cloudiness (estimated as cloud impact factor from global solar radiation) on the intensity of incident EUV radiation were calculated by a non-linear regression model. The total ozone content (TOC) and cloud/surface reflectivity derived from satellite-based measurements were applied into the model for elimination of the uncertainties in measured ozone values. There were two input data of TOC used in the model. The first were taken from the Dobson spectrophotometer measurements (Argentinean Antarctic station Marambio), the second was acquired for geographical coordinates of the Mendel Station from the EOS Aura Ozone Monitoring Instrument and V8.5 algorithm. Analysis of measured EUV data showed that variable cloudiness affected rather short-term fluctuations of the radiation fluxes, while ozone declines caused long-term UV radiation increase in the second half of the year. The model predicted about 98 % variability of the measured EUV radiation. The residuals between measured and modeled EUV radiation intensities were evaluated separately for the above-specified two TOC datasets, parts of seasons and cloud impact factor (cloudiness). The mean average prediction error was used for model validation according to the cloud impact factor and satellite-based reflectivity data.

  7. Parasite sources and sinks in a patched Ross-Macdonald malaria model with human and mosquito movement: Implications for control.

    PubMed

    Ruktanonchai, Nick W; Smith, David L; De Leenheer, Patrick

    2016-09-01

    We consider the dynamics of a mosquito-transmitted pathogen in a multi-patch Ross-Macdonald malaria model with mobile human hosts, mobile vectors, and a heterogeneous environment. We show the existence of a globally stable steady state, and a threshold that determines whether a pathogen is either absent from all patches, or endemic and present at some level in all patches. Each patch is characterized by a local basic reproduction number, whose value predicts whether the disease is cleared or not when the patch is isolated: patches are known as "demographic sinks" if they have a local basic reproduction number less than one, and hence would clear the disease if isolated; patches with a basic reproduction number above one would sustain endemic infection in isolation, and become "demographic sources" of parasites when connected to other patches. Sources are also considered focal areas of transmission for the larger landscape, as they export excess parasites to other areas and can sustain parasite populations. We show how to determine the various basic reproduction numbers from steady state estimates in the patched network and knowledge of additional model parameters, hereby identifying parasite sources in the process. This is useful in the context of control of the infection on natural landscapes, because a commonly suggested strategy is to target focal areas, in order to make their corresponding basic reproduction numbers less than one, effectively turning them into sinks. We show that this is indeed a successful control strategy-albeit a conservative and possibly expensive one-in case either the human host, or the vector does not move. However, we also show that when both humans and vectors move, this strategy may fail, depending on the specific movement patterns exhibited by hosts and vectors. PMID:27436636

  8. Variability and ice production budget in the Ross Ice Shelf Polynya based on a simplified polynya model and satellite observations

    NASA Astrophysics Data System (ADS)

    Nakata, Kazuki; Ohshima, Kay I.; Nihashi, Sohey; Kimura, Noriaki; Tamura, Takeshi

    2015-09-01

    We examined to what degree a simplified polynya model can explain a real polynya based on satellite-derived sea-ice data. In the model, the polynya area, defined as the frazil ice production region, is determined by a balance between the offshore consolidated ice drift and frazil ice production. We used daily polynya area, ice production, and ice drift data derived from AMSR-E. The study area is the Ross Ice Shelf Polynya (RISP), which has the highest sea-ice production in the Southern Ocean. As a modification of the original model to apply the available satellite data set, we introduced the lag time by which produced frazil ice is transported and accumulated at the polynya edge. The model represents a half (48-60%) of the polynya variability when using a lag time of 1.5 days. The frazil ice collection depth at the polynya edge, a key parameter in the model, is estimated to be ˜16 cm. The expansion of the RISP is achieved by ice divergence, and the contraction is achieved mostly by ice production. Both the wind and the remaining components (mainly regarded as the ocean current component) in the ice divergence are larger in the western part of the RISP, which explains the larger extent there. In the one-dimensional frame, assuming that the frazil ice produced within the RISP transforms into consolidated ice with a thickness of 16 cm, the frazil ice production (˜1.7 × 103 m2 d-1) within the RISP approximately balances the export (˜1.6 × 103 m2 d-1) of consolidated thin ice from the RISP edge.

  9. SOUTHBERG: An in-situ investigation of the seismic symphony of Iceberg C16, Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Macayeal, D.; Okal, E. A.; SOUTHBERG Team

    2004-12-01

    We present preliminary results of the operation, from November 2003 to January 2004, of a PASSCAL array of 4 short-period seismometers on Iceberg C16, presently grounded North of Ross Island. A broadband STS-2 instrument was also run at the central station. Results from an uninterrupted 33-day window during which all 4 stations were operational are: (i) GPS tracking indicates that the 4-station polygon remained rigid but drifted (about 20 m) and rotated (0.1 degree) abruptly on Christmas Day; (ii) most of the background seismic noise is concentrated in the 20-50 mHz range, which includes the natural bobbing and rolling frequencies of the ice sheet; (iii) a large variety of seismic signals originating from the ice were detected, including: (Type I) short events featuring a white spectrum, probably simple episodes of cracking in the ice; (Type II) long episodes of relatively broad-band noise, of variable amplitude, lasting hundreds to thousands of seconds, occasionally superimposed over somewhat preferential frequencies; and (Type III) resonant signals featuring extremely narrow spectral lines (with overtones), similar to those recorded in Polynesia in 2000 from drifting icebergs. Type III signals are correlated among the four stations of the network, but do not seem to be interpretable as the mere passage of a seismic wavefront, thereby suggesting the resonance of a normal mode of the whole structure. A Type III signal on 15 January 2004 coincides with an episode of collision with and friction against B-15A, as documented from GPS data obtained on the latter. We may present additional data to be retrieved from Station C16-A, which wintered over, and will be revisited in October 2004.

  10. 33 CFR 162.90 - White River, Arkansas Post Canal, Arkansas River, and Verdigris River between Mississippi River...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., Arkansas River, and Verdigris River between Mississippi River, Ark., and Catoosa, Okla.; use... White River, Arkansas Post Canal, Arkansas River, and Verdigris River between Mississippi River, Ark... apply to: (1) Waterways. White River between Mississippi River and Arkansas Post Canal, Ark.;...

  11. Mutations in nsP1 and PE2 are critical determinants of Ross River virus-induced musculoskeletal inflammatory disease in a mouse model.

    PubMed

    Jupille, Henri J; Oko, Lauren; Stoermer, Kristina A; Heise, Mark T; Mahalingam, Suresh; Gunn, Bronwyn M; Morrison, Thomas E

    2011-02-01

    The viral determinants of alphavirus-induced rheumatic disease have not been elucidated. We identified an RRV strain (DC5692) which, in contrast to the T48 strain, does not induce musculoskeletal inflammation in a mouse model of RRV disease. Substitution of the RRV T48 strain nonstructural protein 1 (nsP1) coding sequence with that from strain DC5692 generated a virus that was attenuated in vivo despite similar viral loads in tissues. In contrast, substitution of the T48 PE2 coding region with the PE2 coding region from DC5692 resulted in attenuation in vivo and reduced viral loads in tissues. In gain of virulence experiments, substitution of the DC5692 strain nsP1 and PE2 coding regions with those from the T48 strain was sufficient to restore full virulence to the DC5692 strain. These findings indicate that determinants in both nsP1 and PE2 have critical and distinct roles in the pathogenesis of RRV-induced musculoskeletal inflammatory disease in mice. PMID:21131014

  12. One new genus and three new species of deep-sea nematodes (Nematoda: Microlaimidae) from the Southwest Pacific Ocean and Ross Sea.

    PubMed

    Leduc, Daniel

    2016-01-01

    New deep-sea nematodes of the family Microlaimidae are described from the Southwest Pacific Ocean and Ross Sea. Microlaimus korari n. sp. is characterised by annulated cuticle with longitudinal bars, round amphideal aperture slightly smaller than the cryptospiral amphideal fovea, spacious and heavily cuticularised buccal cavity with large dorsal tooth and right subventral tooth situated anteriorly relative to left subventral tooth, slender spicules 4.4 cloacal body diameters long, and gubernaculum 1.2 cloacal body diameters long with laterally curved distal end and swollen proximal end. Bolbolaimus tongaensis n. sp. is characterised by annulated cuticle with longitudinal bars, oval amphideal aperture and cryptocircular amphideal fovea situated between cephalic setae and only partially surrounded by cuticle annulations, and short spicules cuticularised along dorsal edge and at proximal end and with swollen portion near proximal end. Maragnopsia n. gen. is characterised by a minute, non-cuticularised mouth cavity without teeth, an elongated posterior pharyngeal bulb more than twice as long as it is wide, a single outstretched testis, and a conico-cylindrical tail 13-16 anal body diameters long. A list of all 83 valid Microlaimus species is provided. The present study provides the first microlaimid species records from deep-sea habitats (> 200 m depth) in the Southwest Pacific and Ross Sea. The presence of M. korari n. sp. on both the continental slope of New Zealand and Ross Sea abyssal plain suggests that this species has a wide geographical and depth distribution. However, molecular analyses will be required to confirm the identity of these two geographically disparate populations. PMID:27396004

  13. Southern McMurdo Sound Project (SMS- ANDRILL): overview of Mid Miocene Climatic Optima events and correlations in western Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Harwood, D. M.; Florindo, F.; Levy, R. H.; Talarico, F.; Fielding, C.; Fischbein, S.; Sms Science Team

    2009-04-01

    The ANtarctic geological DRILLing Program (ANDRILL), an international collaboration between Antarctic research programs of Germany, Italy, New Zealand and the United States, successfully cored in late 2007 (with 98% recovery) a 1138 meter drill hole that documents an excellent history of high latitude paleoenvironmental conditions and climate/glacial variation during Miocene climatic optimum periods. In addition, fracture mapping, core orientation success, and borehole hydrofracture experiments reveal details regarding the history and current stress regime in the western Ross Sea. We present initial correlations of the AND-2A drillcore to global proxies of sea-level and deep-sea geochemical stratigraphy, guided by a robust chronostrati-graphic framework for the early and middle Miocene. Changes evident in stratigraphic sequences, physical properties (borehole and core), and geochemical logs, record fine details of glacial, climatic, tectonic and eustatic influence in the western Ross Sea help establish through correlation to existing records how local changes evident in the drillcore relate to regional and global events. These records combined with paleontological and geochemical evidence for terrestrial - marine paleotemperatures provide important data input for climate and ice-sheet model reconstructions and testing. An abundance of volcanic materials reveals evolution of the McMurdo Volcanic Group, including episodes of explosive volcanism. Substantial subsidence occurred within the last 2 Ma associated with volcanic loading from Ross Island, reversing the persistent littoral to shallow neritic depths evident through most of the cored sequence. Persistent sediment supply into western Victoria Land Basin during a steady phase of thermal subsidence produced a thick stratigraphic sequence from which we are reconstructing the details of paleoclimatic, eustatic and glacial variations on the shallow marine coast of the Transantarctic Mountains.

  14. Shifts in Ross Sea food web structure as indicated by δ15N and δ13C values of fossil Antarctic seals

    NASA Astrophysics Data System (ADS)

    Leopold, A.; Brault, E.; McMahon, K.

    2013-12-01

    As climate change continues to mount, there is a growing need for understanding its effects on biological-physical interactions of marine ecosystems. Assessing the effects of anthropogenic activities on the coastal marine ecosystem involves understanding the underlying mechanisms driving these changes as well as establishing baselines of the natural system. Preliminary findings have indicated shifts in bulk carbon (C) and nitrogen (N) isotopic values of southern elephant seal (Mirounga leonina) samples, collected in the Dry Valleys of Antarctica in the Ross Sea region, over approximately the last 7,000 years. These shifts could result from 1) seals changing their foraging location and/or diet over this time, 2) climate change-induced shifts in the biogeochemistry at the base of the food web, or 3) some combination of both processes. We explored the patterns of long-term change in Ross Sea food web structure by examining the stable isotope values of three top predators in this system, Weddell seals (Leptonychotes weddellii), leopard seals (Hydrurga leptonyx), and crabeater seals (Lobodon carcinophagus). Fossil seal samples were collected in the Dry Valleys during the austral summer of 2012/13 and then analyzed for bulk C and N isotopes via an elemental analyzer/isotope-ratio mass spectrometer (EA/IRMS). Our initial findings indicate that C isotopic values of fossil seal samples from Weddell, leopard, and crabeater seals were more enriched than isotopic values of modern seals of the same species (e.g., δ13C = -22.79 × 0.92 ‰ and -26.71 × 0.50 ‰ for fossil and modern crabeater seals, respectively). Given the relatively consistent diet of crabeater seals, these findings suggest a shift in baseline food web structure occurred over the last 10,000 years, either through changes in foraging location or local shifts in biogeochemistry. For all species, N isotopic values are widely variable (e.g., 7.28 to 16.0 δ15N ‰ for the Weddell seal), which may be a result of

  15. Detailed Ar-Ar Geochronology of Volcanism at Minna Bluff, Antarctica: Two-Phased Growth and Influence on Ross Ice Shelf

    NASA Astrophysics Data System (ADS)

    Ross, J. I.; McIntosh, W. C.; Wilch, T. I.

    2012-12-01

    Minna Bluff has been a significant topographic barrier to the flow of the Ross Ice Shelf since the mid-Miocene. Detailed Ar-Ar analyses of kaersutite and sanidine phenocrysts, and groundmass concentrates from volcanic units indicate an overall west to east progression of volcanic activity. Eruptions of basaltic to intermediate lavas, domes, and scoria cones started at ~12 Ma in at what is now the eastern most point of Minna Bluff, "Minna Hook." Activity was centered in this area for ~4 Ma, constructing a pre-Minna Bluff island. Multiple glacial unconformities found at Minna Hook suggest repeated interaction with large warm-based, erosive ice sheets. Activity migrated westward from Minna Bluff Island at 7-8 Ma closing the gap created by the island and the mainland. Significant edifice construction continued until 4-5 Ma with sporadic and parasitic scoria cone eruptions, possibly associated with Mt. Discovery activity, continuing until 2 Ma. The orientations of Minna Bluff's two major axes are strongly controlled by regional tectonic features. Minna Bluff's E-W axis, McIntosh Cliffs, is sub-parallel to the Radial Lineament and the N-S axis, Minna Hook, appears as extension of faulting bounding the Terror Rift. The constructional evolution of the 70km long volcanic complex has an important role in interpreting the climate signals recovered by the ANDRILL Project. Minna Bluff influenced the material delivered to the AND-1B drill site (ANDRILL MIS 2006-2007) in three critical ways: 1) Minna Bluff diverted upstream material, 2) provided a pinning and stabilizing point for the Ross Ice Shelf, possible controlling the calving line prior to the emergence of Ross Island, and 3) was a significant source of fresh volcanic material throughout much of the period recovered by ANDRILL MIS. For example, a kaersutite-bearing clast recovered from 822.78 mbsf in AND-1B yielded an age of 8.53±0.51 Ma, and was likely derived from Minna Bluff. The results from this study can be

  16. YELLOWSTONE RIVER WATCH (YRW)

    EPA Science Inventory

    Yellowstone River Watch seeks to expand its monitoring and education efforts throughout the Yellowstone River Basin by actively recruiting and training new teacher members. Yellowstone River Watch also seeks to advance existing school programs by offering quality assurance/quali...

  17. Mantle flow deduced from geochemical variations in alkaline magmas of HIMU affinity from continent to ocean, northwestern Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Castillo, P. R.; Panter, K. S.; McIntosh, W. C.

    2011-12-01

    Cenozoic alkaline magmatism in the northwestern Ross Sea (NWRS) region has been recently expanded to include numerous volcanic seamounts on the continental shelf and hundreds more located within the oceanic Adare Basin [1]. The seamounts are Pliocene in age and petrogenetically akin to volcanism on land in the West Antarctic rift system. In general, trace element and Sr-Nd-Pb isotopic data resemble those from ocean islands with HIMU affinity. Apart from the well studied Cameroon volcanic line in West Africa, the NWRS is a unique setting for comparing contemporary alkaline volcanism bridging the transition from oceanic to thinned continental lithosphere adjacent to the thick East Antarctic craton. The geochemistry of NWRS basalts, extending to the northeast from the Mariner Glacier to the Adare Peninsula and into the Adare Basin (~168°E 73°S to ~173°E 70°S), shows a remarkable orderly increase in degree of silica-undersaturation, P2O5, Nb, Zr, Sr contents and La/Yb, Nb/Y, 143Nd/144Nd and 206Pb/204Pb ratios, coupled with a decrease in Ba/La and 87Sr/86Sr ratios, suggesting they were generated from a common heterogeneous mantle source at progressively smaller melt fractions from land to sea. Geochemical variations coincide with northward age propagation in magmatism and southward increase in rifting since the middle Miocene [2]. We propose that the HIMU-like signature in both continental and oceanic sectors is derived from metasomatized lithosphere, whereby the most easily fusible components contribute to the smaller degree melts in greater proportions ocean-ward. Melting may have been triggered by influx of warm asthenosphere initially beneath the continent and then northward by edge-driven convection and channelized by focused extension [3] into the Adare Basin where the metasomatized source is more dispersed. [1] Panter & Castillo (2008) USGS Open-File Report 2007-1047, 069. [2] Granot et al. (2010) Geochem. Geophys. Geosyst. 11(8). [3] Huerta & Harry (2007

  18. Initial Analysis of Internal Layers in the Snow Cover of the Ross Island Region using Ground Penetrating Radar Measurements

    NASA Astrophysics Data System (ADS)

    Kruetzmann, N. C.; George, S. E.; McDonald, A. J.; Rack, W.

    2009-04-01

    In snow and ice, internal layers are created by changes in the ambient conditions at the time of deposition, and represent contrasts in density, electrical conductivity, and ice crystal orientation. By identifying and tracing internal layers in ground penetrating radar (GPR) measurements of the Antarctic snow cover, these layers can be used to measure snow accumulation over time. This is particularly relevant for determining the Antarctic mass balance, as the areal coverage can be greatly expanded from the common, but potentially unrepresentative, point measurements from firn-cores, snow pits, or stake farms. This presentation discusses high-resolution GPR data acquired at three research sites in the vicinity of Scott Base (Antarctica), each site being characterised by different snow and surface properties. The first two sites examined, are located on the flat McMurdo Ice Shelf in zones with significantly different wind and accumulation patterns. The final site is located on the lower slopes of Mt. Erebus (Ross Island), in the dry snow zone, at approximately 350m above sea level. Using a pulseEKKO PRO GPR system, data was acquired at two frequencies simultaneously (500MHz and 1GHz; wavelength in dry snow: 40cm and 20cm, respectively). At the first two sites, transects were collected in an 800m x 800m grid at 100m intervals. Due to difficult terrain, the third site was restricted to a 400m x 400m domain. Radar shots were taken at 5cm intervals along each transect. This both provides a very high horizontal data resolution, and facilitates internal horizon tracking. The acquisition time-window of 135ns allows horizon detection down to a depth of approximately 12m. In order to convert layer depth to accumulation, information on snow density derived from snow pit- and CMP-measurements was also collected. The acquired data provides high-resolution ground-truth information required for the validation of CRYOSAT-2 satellite data (launch date in 2009). An additional reason

  19. Species composition and distribution of the Antarctic plunderfishes (Pisces, Artedidraconidae) from the Ross Sea off Victoria Land

    NASA Astrophysics Data System (ADS)

    La Mesa, Mario; Cattaneo-Vietti, Riccardo; Vacchi, Marino

    2006-04-01

    Among the notothenioid fish, the Antarctic plunderfishes (family Artedidraconidae) are a poorly known component of the bottom fauna of the continental shelf despite their relative importance. The family is composed of 25 small- to medium-sized endemic species and four genera, Artedidraco, Dolloidraco, Histiodraco and Pogonophryne, which are the most benthic and sedentary of the notothenioid fish. In the framework of "Victoria Land Transect Project", several samples of plunderfishes were collected by means of an Agassiz trawl. Sampling activities were carried out between 100 and 500 m depth in five sites over nearly 4° latitude off Victoria Land. Overall, trawling yielded 80 specimens of plunderfish, including all species of Artedidraco reported from the Ross Sea, i.e. Artedidraco glareobarbatus, A. loennbergi, A. orianae, A. shackletoni and A. skottsbergi, and the monotypic genus Histiodraco. The use of multivariate statistical analyses on catch data indicated sampling site as the main factor affecting species composition. Histiodraco velifer and A. skottsbergi were caught almost exclusively in the southernmost sites, characterizing the artedidraconid fauna of Cape Russell. A. orianae was sampled only in the northernmost sites, such as Cape Adare and Hallett Peninsula. A. loennbergi appeared to be a ubiquitous species, whereas A. glareobarbatus was caught only at the Hallett Peninsula. Plunderfishes showed a particular distribution pattern in relation to depth as well. A. glareobarbatus was the shallowest species, being sampled within 100 m. A. orianae and A. shackletoni showed a similar distribution, being caught mostly at 100-200 m, whereas A. skottsbergi was mainly sampled at 200-300 m. H. velifer was caught in a wide depth range, but mostly in deeper waters (400 m). A. loennbergi was eurybathic, showing a wider depth distribution than other species. Univariate measures of diversity indicated Cape Adare as the poorer site in terms of species richness and

  20. Synoptic controls on precipitation pathways and snow delivery to high-accumulation ice core sites in the Ross Sea region, Antarctica

    NASA Astrophysics Data System (ADS)

    Sinclair, K. E.; Bertler, N. A. N.; Trompetter, W. J.

    2010-11-01

    Dominant storm tracks to two ice core sites on the western margin of the Ross Sea, Antarctica (Skinner Saddle (SKS) and Evans Piedmont Glacier), are investigated to establish key synoptic controls on snow accumulation. This is critical in terms of understanding the seasonality, source regions, and transport pathways of precipitation delivered to these sites. In situ snow depth and meteorological observations are used to identify major accumulation events in 2007-2008, which differ considerably between sites in terms of their magnitude and seasonal distribution. While snowfall at Evans Piedmont Glacier occurs almost exclusively during summer and spring, Skinner Saddle receives precipitation year round with a lull during the months of April and May. Cluster analysis of daily back trajectories reveals that the highest-accumulation days at both sites result from fast-moving air masses, associated with synoptic-scale low-pressure systems. There is evidence that short-duration pulses of snowfall at SKS also originate from mesocyclone development over the Ross Ice Shelf and local moisture sources. Changes in the frequency and seasonal distribution of these mechanisms of precipitation delivery will have a marked impact on annual accumulation over time and will therefore need careful consideration during the interpretation of stable isotope and geochemical records from these ice cores.

  1. Soil thermal properties at two different sites on James Ross Island in the period 2012/13

    NASA Astrophysics Data System (ADS)

    Hrbáček, Filip; Láska, Kamil

    2015-04-01

    James Ross Island (JRI) is the largest island in the eastern part of the Antarctic Peninsula. Ulu Peninsula in the northern part of JRI is considered the largest ice free area in the Maritime Antarctica region. However, information about permafrost on JRI, active layer and its soil properties in general are poorly known. In this study, results of soil thermal measurements at two different sites on Ulu Peninsula are presented between 1 April 2012 and 30 April 2013. The study sites are located (1) on an old Holocene marine terrace (10 m a. s. l.) in the closest vicinity of Johann Gregor Mendel (JGM) Station and (2) on top of a volcanic plateau named Johnson Mesa (340 m a. s. l.) about 4 km south of the JGM Station. The soil temperatures were measured at 30 min interval using platinum resistance thermometers Pt100/8 in two profiles up to 200 cm at JGM Station and 75 cm at Johnson Mesa respectively. Decagon 10HS volumetric water content sensors were installed up 30 cm at Johnson Mesa to 50 cm at JGM Station, while Hukseflux HFP01 soil heat flux sensors were used for direct monitoring of soil physical properties at 2.5 cm depth at both sites. The mean soil temperature varied between -5.7°C at 50 cm and -6.3°C at 5 cm at JGM Station, while that for Johnson Mesa varied between -6.9°C at 50 cm and -7.1°C at 10 cm. Maximum active layer thickness estimated from 0 °C isotherm reached 52 cm at JGM Station and 50 cm at Johnson Mesa respectively which corresponded with maximum observed annual temperature at 50 cm at both sites. The warmest part of both profiles detected at 50 cm depth corresponded with maximum thickness of active layer, estimated from 0°C isotherm, reached 52 cm at JGM Station and 50 cm at Johnson Mesa respectively. Volumetric water content at 5 cm varied around 0.25 m3m-3 at both sites. The slight increase to 0.32 m3m-3 was observed at JGM Station at 50 cm and at Johnson Mesa at 30 cm depth. Soil texture analysis showed distinctly higher share of coarser

  2. Lithospheric mantle heterogeneity across the continental-oceanic transition, northwest Ross Sea, Antarctica: new evidence from oxygen isotopes

    NASA Astrophysics Data System (ADS)

    Krans, S. R.; Panter, K. S.; Castillo, P.; Deering, C. D.; Kitajima, K.; Valley, J. W.; Hart, S. R.; Kyle, P. R.

    2013-12-01

    Oxygen isotopes and whole rock chemistry from alkali basalt and basanite in the northwest Ross Sea, Antarctica offer new insight on source heterogeneity across the transition from continental to oceanic lithosphere in a magma-poor rifted margin. In situ SIMS analysis of olivine (Fo 79-90) from the most primitive lavas (MgO ≥ 8 wt%, Mg# 53-70, Ni= 115-338 ppm, Cr= 244-540 ppm) yield an average δ18O = 5.18 × 0.60 ‰ (2σ, n=30) for alkali basalt and 5.25 × 0.44 ‰ (2σ, n=52) for basanite (× 0.28 ‰, 2σ precision on a homogeneous olivine standard). These are similar to the range for olivine from mantle peridotite and HIMU type oceanic basalts (δ18O= 5.0 to 5.4 ‰ and 4.9 to 5.2 ‰, respectively [1]), but with greater variability. Lavas in this region experienced little differentiation, have minimal evidence of crustal contamination (87Sr/86Sr < 0.7030, 143Nd/144Nd > 0.5129), and olivine show no correlation between δ18O and Fo content, further suggesting that the δ18O values are source related. Whole-rock chemistry of alkali basalt and basanite are spatially distributed. In general, alkali basalt is found in thicker continental lithosphere with lower Sr (477-672ppm) and Nb/Y (1.2-2.4) than basanite. Basanite is found in oceanic and thinned continental lithosphere with higher Sr (642-1131 ppm) and Nb/Y (2.4-3.6). Variation in degree of silica-undersaturation and Nb/Y can be explained by varying degree of partial melting. While alkali basalt and basanite can result from varying degrees of partial melting of similar source compositions, the presence of amphibole in mantle xenoliths have lead workers in this region to propose contributions from a metasomatic source [2, 3, 4] with variable 206Pb/204Pb ratios [5]. A negative correlation between Nb/Y and δ18O in both rock types suggests that varying degrees of partial melting are tapping sources with different δ18O values; lower degree melts have δ18O ≤ 5.0 ‰ and higher degree melts have δ18O > 5.3

  3. Iron-oxide Magnetic, Morphologic, and Compositional Tracers of Sediment Provenance and Ice Sheet Extent in the ANDRILL AND-1B Drill Core, Ross Sea, Antarctica (Invited)

    NASA Astrophysics Data System (ADS)

    Brachfeld, S. A.; Pinzon, J.; Darley, J. S.; Sagnotti, L.; Kuhn, G.; Florindo, F.; Wilson, G. S.; Ohneiser, C.; Monien, D.; Joseph, L. H.

    2013-12-01

    The first drilling season of the Antarctic Drilling Program (ANDRILL) recovered a 13.57 million year Miocene through Pleistocene record of paleoclimate change (core AND-1B) within the Ross Sea. The magnetic mineral assemblage records the varying contributions of biological productivity, changing sediment sources, the emergence of volcanic centers, and post-depositional diagenesis. Characterization of bedrock samples from the McMurdo Volcanic Group (MVG) and Transantarctic Mountain (TAM) lithologic units allows us to construct fingerprints for the major source rocks bordering the Ross Sea, and identify their signatures within the AND-1B sediment. Key parameters that can be traced from source rock to sediment for the MVG-derived sediment include a 100-200 C order-disorder transition, titanomaghemite grains with homogenous textures but with substantial Al and Mg content, Fe-spinels with substantial Al, Cr, Mg, and Ti content, and titanomagnetite host grains with 1-3 swarms of ilmenite lamellae (both with variable amounts of oxidation). Distinctive signatures in TAM lithologies include low S-ratios in Koettlitz Group gneisses and Fe-sulfides with magnetite intergrowths in Byrd Glacier basement samples. The Cambrian Granite Harbor Intrusive Complex is characterized by coarse, homogeneous Mn-bearing ilmenite and nearly pure magnetite. The Jurassic dolerites and basalts of the Ferrar Group contain pseudo single domain to stable single domain-sized Fe-oxides with low-Ti content and homogeneous textures. Cu-Fe sulfides are also present in the Ferrar Group. Diamictites in the Pliocene-Pleistocene section of the AND-1B drill core contains Fe-oxide assemblages with MVG-type rock magnetic and textural characteristics, while the Miocene diamictites contain TAM-type signatures. These observations can be explained by increased ice flow from the west during the Miocene and/or the absence of MVG volcanic centers, which had not yet reached a significant size. During the Pliocene and

  4. Fractionation distribution and preliminary ecological risk assessment of As, Hg and Cd in ornithogenic sediments from the Ross Sea region, East Antarctica.

    PubMed

    Lou, Chuangneng; Liu, Xiaodong; Nie, Yaguang; Emslie, Steven D

    2015-12-15

    To evaluate mobility of toxic elements and their potential ecological risk caused by seabird biovectors, the fractionation distributions of arsenic (As), mercury (Hg) and cadmium (Cd) were investigated in three ornithogenic sediment profiles from the Ross Sea region, East Antarctica. The results show residual As holds a dominant position, and Hg mainly derives from residual, organic matter-bound and humic acid-bound fractions, indicating weak mobility of As and Hg. However, exchangeable Cd occupies a considerable proportion in studied samples, suggesting Cd has strong mobility. The preliminary evaluation of Sediment Quality Guidelines (SGQs) shows adverse biological effects may occur occasionally for As and Cd, and rarely for Hg. Using Risk Assessment Code (RAC), the ecological risk is assessed at moderate, low and very high for As, Hg and Cd pollution, respectively. Organic matter derived from guano is the main factor controlling the mobility of Hg and Cd through adsorption and complexation. PMID:26322729

  5. Marine record of late quaternary glacial-interglacial fluctuations in the Ross Sea and evidence for rapid, episodic sea level change due to marine ice sheet collapse

    NASA Technical Reports Server (NTRS)

    Anderson, John B.

    1991-01-01

    Some of the questions to be addressed by SeaRISE include: (1) what was the configuration of the West Antarctic ice sheet during the last glacial maximum; (2) What is its configuration during a glacial minimum; and (3) has it, or any marine ice sheet, undergone episodic rapid mass wasting. These questions are addressed in terms of what is known about the history of the marine ice sheet, specifically in Ross Sea, and what further studies are required to resolve these problems. A second question concerns the extent to which disintegration of marine ice sheets may result in rises in sea level that are episodic in nature and extremely rapid, as suggested by several glaciologists. Evidence that rapid, episodic sea level changes have occurred during the Holocene is also reviewed.

  6. Re-Os systematics of the lithospheric mantle beneath the Western Ross Sea area, Antarctica: depletion ages and dynamic response during rifting

    NASA Astrophysics Data System (ADS)

    Doherty, C.; Class, C.; Goldstein, S. L.; Shirey, S. B.; Martin, A. P.; Cooper, A. F.; Berg, J. H.; Gamble, J. A.

    2013-12-01

    The West Antarctic Rift System (WARS) is situated between the East Antarctic craton and Marie Byrd Land. Seismic studies on the structure of the lithosphere beneath the WARS reveal thinned lithosphere [1] with crustal thickness ranging from 16 to 22 km in the Ross Sea basin [2,3] that is underlain by a low velocity zone at 80-200 km [4]. However, seismic studies alone provide little information on the age of the lithospheric mantle or its fate during rifting and the formation of the WARS. Geochemical studies on lithosphere surrounding Archean cratons have demonstrated the persistence of off-craton Proterozoic lithosphere and potentially Archean lithosphere (e.g. southeast Australia and southern Africa) [5,6], and suggest that it is possible to constrain the age and structure of the lithosphere in the WARS. Os isotope ratios can be used to date the melt depletion events in the asthenosphere that are considered to be equivalent to the stabilization age of the lithospheric mantle [7]. Here we present the first Re-Os isotope measurements on mantle xenoliths from 5.0 to <1.0 Ma-old volcanic rocks collected in a transection from the rift shoulder and into the rift basin in the Western Ross Sea area of the WARS, and suggest that these data can be used to examine the dynamic response of the lithosphere to rifting. For example, ancient Re-depletion ages across this margin could indicate thinning of the lithospheric mantle during continental extension and dynamic extension of the lithospheric mantle beneath the rift basin. In contrast, younger ages might suggest a more complex history or possibly the replacement by asthenosphere as a result of lithospheric delamination during rifting. Our 187Os/188Os isotope ratios show a large range throughout the rifted margin (0.1051 at Foster Crater to 0.1265 on Ross Island), yet define individual melt depletion trends at 7 locations across the rift. Alumachron model ages derived from 187Os/188Os vs. Al2O3 wt% depletion trends reveal

  7. New determinations of 40Ar/39Ar isotopic ages and flow volumes for Cenozoic volcanism in the Terror Rift, Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Rilling, S.; Mukasa, S.; Wilson, T.; Lawver, L.; Hall, C.

    2009-12-01

    This study provides new determinations of 40Ar/39Ar isotopic ages and flow volumes for submarine and subaerial Neogene volcanism developed within the Terror Rift, Ross Sea, Antarctica, the youngest segment of the West Antarctic Rift System. The study is based on the first dredged samples from seven seamounts north of Ross Island, as well as new data from Franklin and Beaufort Islands. The sampled foidite and basanitic lavas range in age from Quaternary (90 ± 66 ka) on a small seamount ˜10 km north of Franklin Island to 6.80 ± 0.05 Ma on Beaufort Island. These ages are consistent with ages of volcanism in both the Melbourne and Erebus Volcanic Provinces and significantly expand the documented area of Neogene magmatism in Victoria Land. There is no geographic progression of volcanism through time, but volcanism was voluminous in the Pliocene and particularly widespread during the Pleistocene. Two of the dredges sampled edifices comprised of less than 0.2 km3 of volcanic materials. The largest seamount in the study area has 58.8 km3 of volcanic material and represents growth over a period of several thousand years. Estimated minimum eruption rates range from 2 × 10-4 km3 y-1 to 2 × 10-3 km3 y-1, consistent with rates proposed for other rift systems and nearby Mt. Erebus. Recent estimates of extension magnitude for the Terror Rift correspond to minimal decompression of only 0.10 to 0.22 GPa and therefore limited melt output of a typical peridotite source.

  8. Brazil: Xingu River

    Atmospheric Science Data Center

    2013-04-18

    ... title:  Fire and Deforestation near the Xingu River     View Larger Image Numerous fires occurred near the headwaters of the Xingu River and the Xingu Indigenous Peoples' Reserve in Mato Grosso, Brazil, during ...

  9. Measuring River Pollution

    ERIC Educational Resources Information Center

    Ayyavoo, Gabriel

    2004-01-01

    The Don River watershed is located within Canada's most highly urbanized area--metropolitan Toronto. Many residential and commercial uses, including alterations to the river's course with bridges, have had a significant impact on the Don's fauna and flora. Pollutants have degraded the river's water quality, a situation exacerbated by the…

  10. Mathematics. Rivers Curriculum Guide.

    ERIC Educational Resources Information Center

    Brueggeman, Gail; Clendenin, Donna

    The Rivers Project at Southern Illinois University began in February, 1990 as a pilot program involving eight high schools along the Mississippi and lower Illinois River. The Rivers Project network has grown through the training of teachers from across the United States and Canada. With scientific literacy as the ultimate goal, students collect…

  11. Rethinking the River.

    ERIC Educational Resources Information Center

    Tenenbaum, David

    1994-01-01

    Examines the ecological impacts of the Mississippi River flood of 1993 and the rethinking of river management practices that has resulted. Provides a map of the flood area which shows the occurrence of rare wildlife found in or near the region's rivers. (LZ)

  12. Flowing with Rivers

    ERIC Educational Resources Information Center

    Anderson, Heather

    2004-01-01

    This article describes a lesson in which students compare how artists have depicted rivers in paintings, using different styles, compositions, subject matter, colors, and techniques. They create a watercolor landscape that includes a river. Students can learn about rivers by studying them on site, through environmental study, and through works of…

  13. Amu Darya River

    Atmospheric Science Data Center

    2013-04-16

    article title:  Amu Darya River     View Larger Image This false-color image of the Amu Darya River was acquired by the Multi-angle Imaging SpectroRadiometer (MISR) in late ... highly vegetated areas to appear red. The Amu Darya river forms a wide delta in the western deserts of Uzbekistan and northeastern ...

  14. Geochemical processes in the Onyx River, Wright Valley, Antarctica: Major ions, nutrients, trace metals

    NASA Astrophysics Data System (ADS)

    Green, William J.; Stage, Brian R.; Preston, Adam; Wagers, Shannon; Shacat, Joseph; Newell, Silvia

    2005-02-01

    We present data on major ions, nutrients and trace metals in an Antarctic stream. The Onyx River is located in Wright Valley (77-32 S; 161-34 E), one of a group of ancient river and glacier-carved landforms that comprise the McMurdo Dry Valleys of Antarctica. The river is more than 30 km long and is the largest of the glacial meltwater streams that characterize this relatively ice-free region near the Ross Sea. The complete absence of rainfall in the region and the usually small contributions of glacially derived tributaries to the main channel make this a comparatively simple system for geochemical investigation. Moreover, the lack of human impacts, past or present, provides an increasingly rare window onto a pristine aquatic system. For all major ions and silica, we observe increasing concentrations with distance from Lake Brownworth down to the recording weir near Lake Vanda. Chemical weathering rates are unexpectedly high and may be related to the rapid dissolution of ancient carbonate deposits and to the severe physical weathering associated with the harsh Antarctic winter. Of the nutrients, nitrate and dissolved reactive phosphate appear to have quite different sources. Nitrate is enriched in waters near the Lower Wright Glacier and may ultimately be derived from stratospheric sources; while phosphate is likely to be the product of chemical weathering of valley rocks and soils. We confirm the work of earlier investigations regarding the importance of the Boulder Pavement as a nutrient sink. Dissolved Mn, Fe, Ni, Cu, and Cd are present at nanomolar levels and, in all cases, the concentrations of these metals are lower than in average world river water. We hypothesize that metal uptake and exchange with particulate phases along the course of the river may serve as a buffer for the dissolved load. Concurrent study of these three solute classes points out significant differences in the mechanisms and sites of their removal from the Onyx River.

  15. Evidence for the Late Cenozoic Antarctic Ice Sheet evolution and bottom current dynamics in the central-western Ross Sea outer margin, Antarctica

    NASA Astrophysics Data System (ADS)

    Kim, Sookwan; De Santis, Laura; Kuk Hong, Jong; Cottlerle, Diego; Petronio, Lorenzo; Colizza, Ester; Bergamasco, Andrea; Kim, Young-Gyun; Kang, Seung-Goo; Kim, Hyoungjun; Kim, Suhwan; Wardell, Nigel; Geletti, Riccardo; McKay, Robert; Jin, Young Keun; Kang, Sung-Ho

    2016-04-01

    Sedimentary records in polar continental margins provide clues for understanding paleo-depositional environments, related to ice sheet evolution and bottom-water current dynamics, during times of past climate and global sea level changes. Previous seismostratigraphic studies of the Ross Sea embayment, Antarctica, illustrated its general stratigraphic framework and the distribution of glacial sedimentary features over the continental shelf, since the onset of Antarctic ice-sheets at the Eocene-Oligocene boundary (~34.0 Ma). In contrast, there are a fewer studies for the outer continental margin, where continuous sedimentary deposits generally preserve the record of past climate cycles with minimum hiatus, comparing to the inner- and mid-continental shelf, where grounding ice streams eroded most of the sediments. Here we present a seismostratigraphic analysis of 2-D multichannel seismic reflection profiles, from the Central Basin located in the central-western Ross Sea outer margin. A glacial prograding wedge developed at the mouth of the Joides Basin since early-middle Miocene times (RSU4: ~14.0 Ma). And the Central Basin was filled with stacked debris-flow deposits and turbidites. The sediment depocenter shifted from the Central Basin toward the slope in the Pliocene (after RSU2: ~3.3 Ma). Pliocene foreset beds are steep and pinch out at the base of the continental slope. Bottom current controlled sediment drifts well developed since the middle Miocene, along the western slope of the central Basin and on the basement highs These areas are far from the mouth of the Joides trough, where most of the glacial sediment is deposited, and they are also more elevated than the basinal areas, where gravity flow maximum thickness accumulated. Along the western slope of the central Basin and over the basement highs, the signature in the sediments of the action of bottom current reworking and shaping the sea floor can be then clearly recognized. We present the sediment drifts

  16. Surface Melt Magnitude Retrieval Over Ross Ice Shelf, Antarctica Using Coupled MODIS Optical and Thermal Satellite Measurements During the 2002-03 Melt Season

    NASA Astrophysics Data System (ADS)

    Karmosky, C. C.; Lampkin, D. J.

    2008-12-01

    Ice shelf stability is of crucial importance in the Antarctic because shelves serve as buttresses to glacial ice advancing from the Antarctic Ice Sheet. Surface melt has been increasing over recent years, especially over the Antarctic Peninsula, contributing to disintegration of shelves such as Larsen. Unfortunately, we are not realistically able to quantify surface snowmelt from ground-based methods because there is sparse coverage in automatic weather stations. Satellite based assessments of melt from passive microwave systems are limited in that they only provide an indication of melt occurrence and have coarse resolution. Though this is useful in tracking the duration of melt, melt amount of magnitude is still unknown. Coupled optical/thermal surface measurements from MODIS were calibrated by estimates of liquid water fraction (LWF) in the upper 1cm of the firn derived from a one-dimensional thermal snowmelt model (SNTHERM). SNTHERM was forced by hourly meteorological data from automatic weather station data at reference sites spanning a range of melt conditions across the Ross Ice Shelf during a particularly intense melt season. Melt intensities or LWF were derived for satellite composite periods covering the Antarctic summer months at a 4km resolution over the entire Ross Ice Shelf, ranging from 0-2 percent LWF in early December to areas along the coast with upwards of 10 percent LWF during the time of peak surface melt. Spatial and temporal variations in the amount of surface melt are seen to be related to both katabatic wind strength and wind shifts due to the progression of cyclones along the circumpolar vortex. Sea ice concentration along the ice shelf front, specifically the formation of polynyas, are also thought to be driving factors for surface melt as latent and sensible heat fluxes increase by one to three orders of magnitude as polynyas form. A future application of surface melt mapping using this empirical retrieval model is to determine melt

  17. Textural characterization, major and volatile element quantification and Ar-Ar systematics of spherulites in the Rocche Rosse obsidian flow, Lipari, Aeolian Islands: a temperature continuum growth model

    NASA Astrophysics Data System (ADS)

    Clay, P. L.; O'Driscoll, B.; Gertisser, R.; Busemann, H.; Sherlock, S. C.; Kelley, S. P.

    2013-02-01

    Spherulitic textures in the Rocche Rosse obsidian flow (Lipari, Aeolian Islands, Italy) have been characterized through petrographic, crystal size distribution (CSD) and in situ major and volatile elemental analyses to assess the mode, temperature and timescales of spherulite formation. Bulk glass chemistry and spherulite chemistry analyzed along transects across the spherulite growth front/glass boundary reveal major-oxide and volatile (H2O, CO2, F, Cl and S) chemical variations and heterogeneities at a ≤5 μm scale. Numerous bulk volatile data in non-vesicular glass (spatially removed from spherulitic textures) reveal homogenous distributions of volatile concentrations: H2O (0.089 ± 0.012 wt%), F (950 ± 40 ppm) and Cl (4,100 ± 330 ppm), with CO2 and S consistently below detection limits suggesting either complete degassing of these volatiles or an originally volatile-poor melt. Volatile concentrations across the spherulite boundary and within the spherulitic textures are highly variable. These observations are consistent with diffusive expulsion of volatiles into melt, leaving a volatile-poor rim advancing ahead of anhydrous crystallite growth, which is envisaged to have had a pronounced effect on spherulite crystallization dynamics. Argon concentrations dissolved in the glass and spherulites differ by a factor of ~20, with Ar sequestered preferentially in the glass phase. Petrographic observation, CSD analysis, volatile and Ar data as well as diffusion modeling support continuous spherulite nucleation and growth starting at magmatic (emplacement) temperatures of ~790-825 °C and progressing through the glass transition temperature range ( T g ~ 750-620 °C), being further modified in the solid state. We propose that nucleation and growth rate are isothermally constant, but vary between differing stages of spherulite growth with continued cooling from magmatic temperatures, such that there is an evolution from a high to a low rate of crystallization and low

  18. Two-stage growth of the Late Miocene Minna Bluff Volcanic Complex, Ross Embayment, Antarctica: implications for ice-sheet and volcanic histories

    NASA Astrophysics Data System (ADS)

    Wilch, T. I.; McIntosh, W. C.; Panter, K. S.; Dunbar, N. W.; Smellie, J.; Fargo, A. J.; Ross, J. I.; Antibus, J. V.; Scanlan, M. K.

    2011-12-01

    Minna Bluff, a 45km long, 5km wide Late Miocene alkaline volcanic peninsula that extends SE into the Ross Ice Shelf, is a major obstruction to ice flow from the south into the McMurdo Sound region. Interpretations of the abundant paleoclimate and glacial history archives, including the ANDRILL records, need to account for the effects of paleogeography on past ice-flow configurations and sediment transport. Mapping and 40Ar/39Ar dating of volcanic sequences indicate that Minna Bluff was constructed between 12 and 4 Ma. The volcanic complex first emerged as an isolated island in the Ross Sea at about 12 Ma. The edifice, here named Minna Hook Island, was constructed between 12 and 8 Ma. During this first stage of growth, regional ice was able to flow through a ~40 km gap between the island and mainland. The second stage of volcanism built the main arm of Minna Bluff, now called McIntosh Cliffs, between 8 and 4 Ma. The second stage resulted in the eruption of exclusively subaerial cinder cones and lava flows. By approximately 5 Ma the peninsula had fully emerged above sea level, fully obstructing ice flow. Evidence for volcano-ice interaction is common in Minna Hook stratigraphic sequences. Well exposed cliff sections exhibit alternations between rocks erupted in subaerial and subaqueous conditions; these sequences are interpreted to represent syneruptive interactions between lava flows and glacial ice and provide evidence for periodic glaciations between 12 and 8 Ma. The lack of coherent horizontal passage zones between subglacial and subaerial lithofacies and the alternating nature of the deposits suggest that the eruptions did not occur in a large stable ice sheet but instead occurred in a more ephemeral local ice cap or rapidly drained ice sheet. At least two widespread, undulating glacial unconformities mantled by glacial and fluvial sediments are exposed near the base of the Minna Hook sequences. These unconformities record broad scale Antarctic Ice Sheet events

  19. Phytoplankton assemblages and lipid biomarkers indicate sea-surface warming and sea-ice decline in the Ross Sea during Marine Isotope sub-Stage 5e

    NASA Astrophysics Data System (ADS)

    Hartman, Julian D.; Sangiorgi, Francesca; Peterse, Francien; Barcena, Maria A.; Albertazzi, Sonia; Asioli, Alessandra; Giglio, Federico; Langone, Leonardo; Tateo, Fabio; Trincardi, Fabio

    2016-04-01

    The Marine Isotope sub-Stage 5e (~ 125 - 119 kyrs BP), the last interglacial period before the present, is believed to have been globally warmer (~ 2°C) than today. Studying this time interval might therefore provide insights into near future climate state given the ongoing climate change and global temperature increase. Of particular interest are the expected changes in polar ice cover. One important aspect of the cryosphere is sea-ice, which influences albedo, deep and surface water currents, and phytoplankton production, and thus affects the global climate system. To investigate whether changes in sea-ice cover occurred in the Southern Ocean close to Antarctica during Marine Isotope sub-Stage 5e dinoflagellate and diatom assemblages have been analyzed in core AS05-10, drilled in the continental slope off the Drygalski basin (Ross Sea) at a water depth of 2377 m. The core was drilled within the frame of the PNRA 2009/A2.01 project, an Italian project with a multidisciplinary approach, and covers the interval from Present to Marine Isotope Stage (MIS) 7. The core stratigraphy is based on diatom bioevents and on the climate cyclicity provided by the variations of the diatom assemblages. For this study we focused on the interval from MIS7 to MIS5. A strong reduction of sea-ice-loving diatom taxa with respect to open water-loving diatom taxa is observed during MIS5. In general the production of phytoplankton increases at the base of MIS5 and then slowly decreases. Dinoflagellate cysts, particularly heterotrophic species, are abundant during MIS5e only. The sea surface temperature reconstruction based on the TEX86L, a proxy based on lipid biomarkers produced by Thaumarcheota, shows a 4°C temperature increase from MIS6 to MIS5e. A slightly smaller temperature increase is observed at the onset of MIS7, but this stage is barren of heterotrophic dinoflagellates. All proxies together seem to indicate that the retreat of the summer sea-ice in the Ross Sea during MIS5e was

  20. CHARACTERIZATION OF BACTERIAL BIOMASS IN MARINE SEDIMENTS BENEATH THE ROSS ICE SHEET, ANTARCTICA BY PHOSPHOLIPIDS ANALYSIS AND 16S RRNA GENE SEQUENCING

    NASA Astrophysics Data System (ADS)

    Carr, S. A.; Glossner, A. W.; Dunbar, R. B.; Vogel, S. W.; Brandes, J.; Sahl, J. W.; Pepe-Ranney, C.; Spear, J. R.; Naish, T.; Powell, R. D.; Mandernack, K. W.

    2009-12-01

    As concerns regarding climate change increase, so does the importance of understanding the biogeochemical cycling of elements such as carbon. In the marine sediments of the Ross Sea, Antarctica, the in situ microbial community plays a significant role in the decomposition, mineralization and recycling of both organic and inorganic carbon. In this study, viable biomass for the top 155 cm below seafloor of sediment cores in the Ross Sea were estimated based on microbial phospholipid concentrations and Acridine Orange direct cell counts (AODC). Results for the biomass estimates suggest that both methods are able to accurately estimate viable biomass. Structural and isotopic analyses of phospholipid fatty acids (PLFAs) and phospholipid ether lipids (PELs), as well as isotopic analyses of carbon sources within sediment porewaters were used to identify changes in microbial metabolic pathways. The δ13C values of dissolved inorganic carbon (DIC) in porewaters ranged from -2.52‰ to -3.72‰ while corresponding δ13C values for sedimentary organic carbon (OC) varied from -26.25‰ to -23.12‰ in the surface and 155cm porewaters, respectively. The δ13C values of PLFAs are slightly lighter than the δ13C values of the organic carbon, ranging between -29‰ to -35‰ throughout the sediment core. 16S ribosomal RNA gene sequencing was preformed to classify the microbial species present at various depths. 16S sequences revealed that members of this microbial community include α, δ, ɛ, and γ proteobacteria, acitobacteria, acidobacteria, and flavobacteria, all of which have been previously sequenced from other Antarctic continental shelf sediments. Archaea represent 1 to 3% of the microbial community which is similar to comparable studies. Amongst the sequenced organisms, many have been reported to utilize organic carbon sources such as amino acids, oligosaccharides, and lactose. These heterotropic organisms compliment the constant lipid isotope values and suggest that

  1. Constraining the dynamic response of subcontinental lithospheric mantle to rifting using Re-Os model ages in the Western Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Doherty, C.; Class, C.; Goldstein, S. L.; Shirey, S. B.; Martin, A. P.; Cooper, A. F.; Berg, J. H.; Gamble, J. A.

    2012-12-01

    In order to understand the dynamic response of the subcontinental lithospheric mantle (SCLM) to rifting, it is important to be able to distinguish the geochemical signatures of SCLM vs. asthenosphere. Recent work demonstrates that unradiogenic Os isotope ratios can indicate old depletion events in the convecting upper mantle (e.g. Rudnick & Walker, 2009), and allow us to make these distinctions. Thus, if SCLM can be traced across a rifted margin, its fate during rifting can be established. The Western Ross Sea provides favorable conditions to test the dynamic response of SCLM to rifting. Re-Os measurements from 8 locations extending from the rift shoulder to 200 km into the rift basin reveal 187Os/188Os ranging from 0.1056 at Foster Crater on the shoulder, to 0.1265 on Ross Island within the rift. While individual sample model ages vary widely throughout the margin, 'aluminochron' ages (Reisberg & Lorand, 1995) reveal a narrower range of lithospheric stabilization ages. Franklin Island and Sulfur Cones show a range of Re-depletion ages (603-1522 Ma and 436-1497 Ma) but aluminochrons yield Paleoproterozoic stabilization ages of 1680 Ma and 1789 Ma, respectively. These ages coincide with U-Pb zircon ages from Transantarctic Mountain (TAM) crustal rocks, in support of SCLM stabilization at the time of crust formation along the central TAM. The Paleoproterozoic stabilization age recorded at Franklin Island is especially significant, since it lies 200km off of the rift shoulder. The similar ages beneath the rift shoulder and within the rift suggests stretched SCLM reaches into the rift and thus precludes replacement by asthenospheric mantle. The persistence of thinned Paleoproterozoic SCLM into the rifted zone in WARS suggests that it represents a 'type I' margin of Huismans and Beaumont (2011), which is characterized by crustal breakup before loss of lithospheric mantle. The Archean Re-depletion age of 3.2 Ga observed on the rift shoulder suggests that cratonic

  2. Geochemical provenance analyses on ANDRILL SMS (AND-2A) core: Evidence for Miocene ice-flow directions in the Ross embayment, Antarctica

    NASA Astrophysics Data System (ADS)

    Hoffmann, S.; von Eynatten, H.; Kuhn, G.

    2009-12-01

    ANDRILL (ANtarctic geological DRILLing) completed in 2007 the AND-2A sediment drillcore from the Southern McMurdo Sound Project (SMS) in the Ross Sea, Antarctica. The main target of the Project was to recover an ice-proximal drillcore, which contain the transition from a warming period during the Middle Miocene Climate Optimum (MMO, 15-17 Ma) to the today permanent ice sheet. After recovering, the AND-2A drillcore comprises an almost undisturbed ~600 m thick section of Miocene strata (800-223 m). Particular, the Middle Miocene strata in the core has the potential to understand the behaviour of the Ross Ice system and the adjacent outlet glacier of the East Antarctic Ice Sheet (EAIS) during a pronounced warm period (MMO). Bulk rock geochemical analyses on diamictites and silt-, mudstone are the appropriate method to determine the source rocks from the surrounding area and as result the ice-flow direction in high frequency downcore. Geochemical analyses of the AND-2A drillcore were carried out with an Avaatech XRF Core Scanner (XRF-CS) and on discrete samples. The geochemical composition of the sediment was analysed by the XRF-CS with a downcore resolution of least 10 cm. Discrete samples for bulk rock analysis were taken from about each meter of the core and were analyses by conventional XRF. According to multivariate statistic (Principal Component Analysis, PCA) on the geochemical dataset, the AND-2A core is mainly controlled by a (i) Ce, Nb, La, Y, Zr component and a (ii) Cr, Ni component. The first (i) component could be related to heavy minerals (REE-Phosphates, Zircon etc.) from felsic source rocks. Especially, the high content on Zr (up to 550 ppm) and Ce (up to 140 ppm) can be a result of weathering and enrichment of the corresponding heavy minerals in the sediment. The second component (ii) seems to be reflecting a mafic source from the McMurdo Volcanic Group and/or dolerites from the Ferrar Supergroup. Moreover, by applying cluster analysis on diamictites

  3. 76 FR 51887 - Safety Zone; Patuxent River, Patuxent River, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-19

    ...) entitled ``Safety Zone; Patuxent River, Patuxent River, MD'' in the Federal Register (76 FR 36447). We... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Patuxent River, Patuxent River, MD AGENCY... safety zone during the ``NAS Patuxent River Air Expo '11,'' which consists of aerial...

  4. First discovery of a new species of Newmanella Ross, 1969 (Balanomorpha: Tetraclitidae) in the western Pacific, with a note on the new status of Neonrosella Jones, 2010.

    PubMed

    Chan, Benny K K; Cheang, Chi Chiu

    2016-01-01

    The present study describes a new species of Newmanella Ross, 1969 (Thoracica: Tetraclitidae: Newmanellinae) from Taiwan. Species in this genus are believed to be distributed in tropical western Atlantic waters and the present study is the first report of a new species of Newmanella in the western Pacific. Newmanella spinosus sp. nov. is morphologically close to N. radiata Bruguiére, 1789 but it is distinguished from N. radiata by the morphology of the scutum, tergum, cirrus II, mandible and maxillule. Sequence divergence of 12S rDNA between N. radiata and N. spinosus sp. nov. reached 7.6%, suggesting these are two different species. Newmanella spinosus sp. nov. is distributed in the Philippines, Taiwan and Okinawa but is absent from Hong Kong, Hainan and China. The distribution is probably affected by the Kuroshio Current. The subfamily Newmanellinae Ross and Perreault, 1999 contains two genera, Newmanella and Yamaguchiella Ross & Perreault, 1999. Neonrosella Jones, 2010 is a subgenus of Yamaguchiella. A recent molecular analysis (Tsang et al. 2015) determined that Yamaguchiella and Neonrosella are located in two distinct and distantly-related clades within the tetraclitid clade, suggesting that the subgenus Neonrosella is not closely related to Yamaguchiella and should be elevated to generic status. PMID:27394583

  5. Reconsidering Himalayan river anticlines

    NASA Astrophysics Data System (ADS)

    Montgomery, David R.; Stolar, Drew B.

    2006-12-01

    The observation that major Himalayan rivers flow parallel to and down the axis of anticlines oriented transverse to the primary structural grain of the range has puzzled geomorphologists for decades. Although there is a general consensus that the courses of trans-Himalayan rivers predate the Himalayan orogeny, the close association of rivers and structural highs would not be expected to result from the superposition of rivers onto pre-existing structures. Moreover, in the past several decades structural studies have shown that the development of river anticlines represents the most recent phase of deformation in the range. It is proposed that Himalayan river anticlines are the consequence of focused rock uplift in response to significant differences between net erosion along major rivers and surrounding regions. This hypothesis is supported by large gradients in observed and predicted erosion rates across major Himalayan rivers and by results from an isostasy-driven model, which requires relatively low flexural rigidities to match the wavelength of Himalayan river anticlines. Whether the amplitude of these structures is due to isostasy or also reflects active crustal channeling is not well-constrained, but given the uncertainty in the flexural rigidity and in the local and far-field erosion rates, both possibilities remain viable explanations. Given the observed correlation between the Arun River anticline and local rainfall maxima, it is proposed that Himalayan river anticlines are the expression of a relatively fine-scale linkage between tectonics, erosion and climate superimposed on the broader and older canvas of the Himalayan orogeny. Finally, it is suggested that the development of river anticlines represents one example along a continuum of features arising from different degrees of erosion-structure coupling in active orogens.

  6. Rivers: Nature's Wondrous Waterways.

    ERIC Educational Resources Information Center

    Harrison, David L.

    Rivers play a vital role in the life of the planet. They provide water for wildlife, plant life, and people, and they help to fertilize fields where corn and other crops grow. But how were these rivers made? This children's book takes readers/students on a journey down a river from its source at the top of a mountain to its mouth where it meets…

  7. Bathymetry and geological structures beneath the Ross Ice Shelf at the mouth of Whillans Ice Stream, West Antarctica, modeled from ground-based gravity measurements

    NASA Astrophysics Data System (ADS)

    Muto, A.; Christianson, K.; Horgan, H.; Anandakrishnan, S.; Alley, R. B.

    2012-12-01

    Grounding zones of ice sheets and contiguous ice shelves are important in understanding ice sheet dynamics, as key processes that influence the grounded ice and its discharge into the ocean occur in these regions. Ice-ocean interactions are controlled by the relatively poorly known bathymetry and the configuration of the cavity beneath ice shelves. In addition, knowledge of submarine geological structures and their distributions contributes to understanding the dynamic history of the glaciers and ice streams feeding the ice shelves. However, detailed geophysical surveys of these areas remain scarce due largely to the logistic difficulties of obtaining observational data about the subglacial environment beneath an ice shelf. Here we present a 3D model of the bathymetry and geological structures beneath the Ross Ice Shelf in an embayment at the mouth of Whillans Ice Stream. We use gravity data collected at 82 locations with a portable gravimeter, in conjunction with high-resolution active-source seismic and ice-penetrating radar data to constrain thicknesses of the water column, sediments, ice and firn where the data sets overlap. The active-source seismic survey revealed a shallow water column and soft sediments approximately 15 km seaward of the grounding zone. We explore the extent of such water and sedimentary columns, and the density of the sediment, in a ~500 km-2 embayment that is roughly triangular in shape. Finally, we discuss the uncertainties and trade-offs of the various methods.

  8. Caesarean delivery in a parturient with a femoro-femoral crossover graft and congenital aortic stenosis repaired by the Ross procedure.

    PubMed

    Richardson, P; Whittaker, S; Rajesh, U; Bonduelle, M; Morgan, J; Garry, M; Weston, C; Ferguson, C; Fligelstone, L

    2009-10-01

    We report a case of a patient with congenital aortic stenosis previously repaired using the Ross procedure, who presented to our unit for urgent caesarean delivery. Management was complicated by moderate residual cardiac disease and the presence of a suprapubic femoro-femoral crossover graft. Following application of five-lead electrocardiogram and invasive blood pressure monitoring, anaesthesia was induced via combined spinal-epidural with epidural volume extension. A high transverse surgical approach avoided the course of the vascular graft, while further precautions included the immediate availability of vascular surgeons and cell salvage. Our anaesthetic technique was tailored to minimise disruption to cardiovascular function, and in particular to limit regurgitant flow across the pulmonary valve. This case highlights the value of early identification of high-risk parturients and multidisciplinary involvement at delivery. Risk stratification in the patient with grown-up congenital heart disease is based upon timely evaluation of the underlying congenital pathology, surgical history and subsequent functional status. PMID:19703763

  9. Student-Designed River Study.

    ERIC Educational Resources Information Center

    Turkall, Sheila Florian

    1996-01-01

    Describes an integrated student-designed investigation in which students explore different aspects of the Chagrin River including the river ecosystem, velocity and average depth, river flooding, water quality, and economic and political factors. (JRH)

  10. River and Stream Pollution

    MedlinePlus

    ... Pollution Dirt Dirt is a big cause of pollution in our rivers and streams. Rain washes dirt into streams and rivers. Dirt can smother fish and other animals that live in the water. If plants can't get enough sunlight because ...

  11. Hudson River School

    ERIC Educational Resources Information Center

    McCloskey, Patrick J.

    2004-01-01

    In this article, the author features the "Clearwater," a full-size working replica of a 19th century Hudson River cargo sloop. The "Clearwater" has been serving New York state students as a link to both local history and the environment, helping them to learn lessons about the history of the Hudson River and the environment, thereby supplementing…

  12. Mississippi River. [Lesson Plan].

    ERIC Educational Resources Information Center

    Buchberg, Wendy

    Based on novels and books about the Mississippi River, this lesson plan presents activities designed to help students understand that the Mississippi River has made its mark on America's geography, commerce, and literature; and that booktalks provide a summary, explains what kind of reader the book will appeal to, and may also contain a oral…

  13. Alaska Glaciers and Rivers

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image on October 7, 2007, showing the Alaska Mountains of south-central Alaska already coated with snow. Purple shadows hang in the lee of the peaks, giving the snow-clad land a crumpled appearance. White gives way to brown on the right side of the image where the mountains yield to the lower-elevation Susitna River Valley. The river itself cuts a silver, winding path through deep green forests and brown wetlands and tundra. Extending from the river valley, are smaller rivers that originated in the Alaska Mountains. The source of these rivers is evident in the image. Smooth white tongues of ice extend into the river valleys, the remnants of the glaciers that carved the valleys into the land. Most of the water flowing into the Gulf of Alaska from the Susitna River comes from these mountain glaciers. Glacier melt also feeds glacier lakes, only one of which is large enough to be visible in this image. Immediately left of the Kahiltna River, the aquamarine waters of Chelatna Lake stand out starkly against the brown and white landscape.

  14. One river, many stories

    EPA Science Inventory

    Interactive exhibition elements include opportunity to add stories, drawings, and place names to maps of the river; record & share your vision for the river with public television. The Duluth Art Institute will present the kick-off event for the month-long media focus around ...

  15. The Illinois Rivers Project.

    ERIC Educational Resources Information Center

    Williams, Robert A.; And Others

    The Illinois Rivers Project was developed as an integrated, multidimensional science/technology/society pilot project designed to introduce water quality dimensions into Illinois high schools. The project involved high school science, social science, and English teachers in an integrated study of their local river and community. Science students…

  16. Seasonal variation of meteorological variables and recent surface ablation / accumulation rates on Davies Dome and Whisky Glacier, James Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Láska, K.; Nývlt, D.; Engel, Z.; Budík, L.

    2012-04-01

    In this study, surface mass balance data of two glaciers on James Ross Island, Antarctica, and its spatial and temporal variations are evaluated using snow ablation stakes, ground-penetrating radar, and dGPS measurements. The investigated glaciers are located on the Ulu Peninsula, northern part of James Ross Island. Davies Dome is an ice dome, which originates on the surface of a flat volcanic mesa at elevations >400 m a.s.l. and terminates with a single 700 m wide outlet in the Whisky Bay. Davies Dome has an area of ~6.5 km2 and lies in the altitude range of 0-514 m a.s.l. Whisky Glacier is a cold-based land-terminating valley glacier surrounded by an extensive moraine ridges made of debris-covered ice. The glacier has an area of ~2.4 km2 and lies in the altitude range of 215-520 m a.s.l. Within several summer austral summers, extensive field programme were carried out on both glaciers including the operation of two automatic weather stations, field mapping and mass balance measurements. Each station was equipped with albedometer CM7B (Kipp-Zonen, Netherlands), air temperature and humidity sensor EMS33 (EMS, Czech Republic), propeller anemometer 05103 (Young, USA), and snow depth sensors (Judd, USA). In the period 2009-2011, high seasonal and interdiurnal variability of incoming solar radiation and near-surface air temperature was found as a result of changes in the circulation patterns and synoptic-scale weather systems moving in the Circumpolar Trough. High ablation and accumulation rates were recorded mainly in the spring and summer seasons (October-February), while negligible changes were found in winter (May-September). The effects of positive degree-day temperatures on the surface ablation rates were examined using a linear regression model. In this approach, near-surface air temperature maps on the glacier surfaces were derived from digital elevation model according to actual temperature lapse rates. Mass balance investigations started in 2006 on Davies

  17. A method for assessing the physical recovery of Antarctic desert pavements following human-induced disturbances: a case study in the Ross Sea region of Antarctica.

    PubMed

    O'Neill, Tanya A; Balks, Megan R; López-Martínez, Jerónimo; McWhirter, Judi L

    2012-12-15

    With increasing visitor numbers an understanding of the impacts of human activities in Antarctic terrestrial environments has become important. The objective of this study was to develop a means for assessing recovery of the ground surface desert pavement following physical disturbance. A set of 11 criteria were identified to assess desert pavement recovery. Assessed criteria were: embeddedness of surface clasts; impressions of removed clasts; degree of clast surface weathering; % overturned clasts; salt on underside of clasts; development of salt coatings; armouring per m(2); colour contrast; evidence of subsidence/melt out; accumulation of salt on cut surfaces; and evidence of patterned ground development. Recovery criteria were assigned a severity/extent rating on a scale from zero to four, zero being highly disturbed, and four being undisturbed. A relative % recovery for each criteria was calculated for each site by comparison with a nearby undisturbed control area, and an overall Mean Recovery Index (MRI) was assigned to each pavement surface. To test the method, 54 sites in the Ross Sea region of Antarctica were investigated including areas disturbed by: bulldozer scraping for road-fill, contouring for infrastructure, geotechnical investigations, and experimental treading trial sites. Disturbances had occurred at timescales ranging from one week to 50 years prior to assessment. The extent of desert pavement recovery at the sites investigated in this study was higher than anticipated. Fifty of the 54 sites investigated were in an intermediate, or higher, stage of desert pavement recovery, 30 sites were in an advanced stage of recovery, and four sites were indistinguishable from adjacent control sites (MRI = 100%). It was found that active surfaces, such as the gravel beach deposits at the Greenpeace World Park Base site at Cape Evans, the aeolian sand deposits at Bull Pass, and the alluvial fan deposits of the Loop Moraine field campsite, recovered relatively

  18. 2. View of Tombigbee River Bridge facing southeast. River flow ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. View of Tombigbee River Bridge facing southeast. River flow is to left. South Pony span in background is not clearly shown. North pony span is shown on the left of main span. - Tombigbee River Bridge, Spanning Tombigbee River at State Highway 182, Columbus, Lowndes County, MS

  19. 36 CFR 7.89 - New River Gorge National River.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... River Gorge National River? (i) In addition to the applicable provisions in 36 CFR part 4, all... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false New River Gorge National River. 7.89 Section 7.89 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF...

  20. 33 CFR 117.734 - Navesink River (Swimming River).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Navesink River (Swimming River... BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.734 Navesink River (Swimming River). The Oceanic Bridge, mile 4.5, shall open on signal; except that, from December 1...

  1. 33 CFR 117.734 - Navesink River (Swimming River).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Navesink River (Swimming River... BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.734 Navesink River (Swimming River). The Oceanic Bridge, mile 4.5, shall open on signal; except that, from December 1...

  2. 33 CFR 117.734 - Navesink River (Swimming River).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Navesink River (Swimming River... BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.734 Navesink River (Swimming River). The Oceanic Bridge, mile 4.5, shall open on signal; except that, from December 1...

  3. 33 CFR 117.734 - Navesink River (Swimming River).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Navesink River (Swimming River... BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.734 Navesink River (Swimming River). The Oceanic Bridge, mile 4.5, shall open on signal; except that, from December 1...

  4. 33 CFR 117.734 - Navesink River (Swimming River).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Navesink River (Swimming River... BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.734 Navesink River (Swimming River). The Oceanic Bridge, mile 4.5, shall open on signal; except that, from December 1...

  5. 36 CFR 7.89 - New River Gorge National River.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false New River Gorge National River. 7.89 Section 7.89 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.89 New River Gorge National River....

  6. The impact of glacier retreat from the Ross Sea on local climate: Characterization of mineral dust in the Taylor Dome ice core, East Antarctica

    NASA Astrophysics Data System (ADS)

    Aarons, S. M.; Aciego, S. M.; Gabrielli, P.; Delmonte, B.; Koornneef, J. M.; Wegner, A.; Blakowski, M. A.

    2016-06-01

    Recent declines in ice shelf and sea ice extent experienced in polar regions highlight the importance of evaluating variations in local weather patterns in response to climate change. Airborne mineral particles (dust) transported through the atmosphere and deposited on ice sheets and glaciers in Antarctica and Greenland can provide a robust set of tools for resolving the evolution of climatic systems through time. Here we present the first high time resolution radiogenic isotope (strontium and neodymium) data for Holocene dust in a coastal East Antarctic ice core, accompanied by rare earth element composition, dust concentration, and particle size distribution during the last deglaciation. We aim to use these combined ice core data to determine dust provenance, with variations indicative of shifts in either dust production, sources, and/or transport pathways. We analyzed a series of 17 samples from the Taylor Dome (77°47‧47″S, 158°43‧26″E) ice core, 113-391 m in depth from 1.1-31.4 ka. Radiogenic isotopic and rare earth element compositions of dust during the last glacial period are in good agreement with previously measured East Antarctic ice core dust records. In contrast, the Holocene dust dataset displays a broad range in isotopic and rare earth element compositions, suggesting a shift from long-range transported dust to a more variable, local input that may be linked to the retreat of the Ross Ice Shelf during the last deglaciation. Observed changes in the dust cycle inferred from a coastal East Antarctic ice core can thus be used to infer an evolving local climate.

  7. Valuation of Indonesian catastrophic earthquake bonds with generalized extreme value (GEV) distribution and Cox-Ingersoll-Ross (CIR) interest rate model

    NASA Astrophysics Data System (ADS)

    Gunardi, Setiawan, Ezra Putranda

    2015-12-01

    Indonesia is a country with high risk of earthquake, because of its position in the border of earth's tectonic plate. An earthquake could raise very high amount of damage, loss, and other economic impacts. So, Indonesia needs a mechanism for transferring the risk of earthquake from the government or the (reinsurance) company, as it could collect enough money for implementing the rehabilitation and reconstruction program. One of the mechanisms is by issuing catastrophe bond, `act-of-God bond', or simply CAT bond. A catastrophe bond issued by a special-purpose-vehicle (SPV) company, and then sold to the investor. The revenue from this transaction is joined with the money (premium) from the sponsor company and then invested in other product. If a catastrophe happened before the time-of-maturity, cash flow from the SPV to the investor will discounted or stopped, and the cash flow is paid to the sponsor company to compensate their loss because of this catastrophe event. When we consider the earthquake only, the amount of discounted cash flow could determine based on the earthquake's magnitude. A case study with Indonesian earthquake magnitude data show that the probability of maximum magnitude can model by generalized extreme value (GEV) distribution. In pricing this catastrophe bond, we assumed stochastic interest rate that following the Cox-Ingersoll-Ross (CIR) interest rate model. We develop formulas for pricing three types of catastrophe bond, namely zero coupon bonds, `coupon only at risk' bond, and `principal and coupon at risk' bond. Relationship between price of the catastrophe bond and CIR model's parameter, GEV's parameter, percentage of coupon, and discounted cash flow rule then explained via Monte Carlo simulation.

  8. Valuation of Indonesian catastrophic earthquake bonds with generalized extreme value (GEV) distribution and Cox-Ingersoll-Ross (CIR) interest rate model

    SciTech Connect

    Gunardi,; Setiawan, Ezra Putranda

    2015-12-22

    Indonesia is a country with high risk of earthquake, because of its position in the border of earth’s tectonic plate. An earthquake could raise very high amount of damage, loss, and other economic impacts. So, Indonesia needs a mechanism for transferring the risk of earthquake from the government or the (reinsurance) company, as it could collect enough money for implementing the rehabilitation and reconstruction program. One of the mechanisms is by issuing catastrophe bond, ‘act-of-God bond’, or simply CAT bond. A catastrophe bond issued by a special-purpose-vehicle (SPV) company, and then sold to the investor. The revenue from this transaction is joined with the money (premium) from the sponsor company and then invested in other product. If a catastrophe happened before the time-of-maturity, cash flow from the SPV to the investor will discounted or stopped, and the cash flow is paid to the sponsor company to compensate their loss because of this catastrophe event. When we consider the earthquake only, the amount of discounted cash flow could determine based on the earthquake’s magnitude. A case study with Indonesian earthquake magnitude data show that the probability of maximum magnitude can model by generalized extreme value (GEV) distribution. In pricing this catastrophe bond, we assumed stochastic interest rate that following the Cox-Ingersoll-Ross (CIR) interest rate model. We develop formulas for pricing three types of catastrophe bond, namely zero coupon bonds, ‘coupon only at risk’ bond, and ‘principal and coupon at risk’ bond. Relationship between price of the catastrophe bond and CIR model’s parameter, GEV’s parameter, percentage of coupon, and discounted cash flow rule then explained via Monte Carlo simulation.

  9. Parasite Communities of Icefish (Chionodraco hamatus) in the Ross Sea (Antarctica): Influence of the Host Sex on the Helminth Infracommunity Structure

    PubMed Central

    Santoro, Mario; Mattiucci, Simonetta; Cipriani, Paolo; Bellisario, Bruno; Romanelli, Francesco; Cimmaruta, Roberta; Nascetti, Giuseppe

    2014-01-01

    Parasite communities of Chionodraco hamatus were investigated from Terra Nova Bay (Ross Sea, Antarctica) during host spawning time. Special attention was given to helminth infracommunities and effect of host sex on its structure. A total of 21 taxa including 5 ecto-parasites and 16 endo-parasites were identified. The number of ecto and endo-parasite species per individual host ranged from 1 to 3 and 3 to 10, respectively, while the mean numbers of parasite specimens per individual host were 4.7 and 1309.7, respectively. The rich abundance of infection suggests a rich concentration of helminth intermediate/paratenic hosts in the coastal waters of Terra Nova Bay. Chionodraco hamatus serves as a definitive host for 10 helminth taxa, while it acts as an intermediate/paratenic host for 6 helminth taxa. Larvae of 6 helminth taxa for which C. hamatus serves as intermediate/paratenic host represented 98.7% of all specimens found. Of these, the tetraphyllidean and diphyllobothridean cestodes and the nematode Contracaecum osculatum s.l. were the most prevalent and abundant. ‘Larval’ infracommunities had significantly higher species richness, total abundance and diversity than ‘adult’ infracommunities, suggesting the important role of C. hamatus in supporting the life cycles of those parasites in the study area as a paratenic/intermediate host. Significant differences in the pattern of helminth infracommunities of larval forms between male and female fish were found. These differences could be caused by physiological, and most probably by behavioral differences between sexes suggesting that sex is an important factor influencing parasite burden in C. hamatus during reproductive season. PMID:24558440

  10. The Growth Performance, Carcass Characteristics, and Meat Quality of Egg-Type Male Growing Chicken and White-Mini Broiler in Comparison with Commercial Broiler (Ross 308)

    PubMed Central

    Kim, Hyun-Wook; Kim, Cheon-Jei; Kim, Eun-Jib; Kim, Hee-Sung

    2014-01-01

    The present study was conducted to compare the growth performance, carcass characteristics, and meat quality of the egg-type male growing chicken (EM), white-mini broiler (WB), and commercial broiler (Ross 308, CB). A total of 360 1-d-old chicks were reared together using a completely randomized design with 4 replicates for each group under the identical feeding and rearing conditions. The ADG and gain:feed were the highest in CB, intermediate in WB, and the lowest in EM (p<0.05), and the live and carcass weights of CB and EM were significantly higher than those of WB (p<0.05). The pH of breast meat from WB and CB was significantly higher (p<0.05) than that from EM with a similar body weight. The EM had the lowest moisture (p<0.05) and the highest protein content (p<0.05), whereas the fat and ash contents were not different among groups. The mystiric acid (C14:0), palmitoleic acid (C16:1 ω7), and oleic acid (C18:1 ω9) levels were significantly higher in breast meat from CB (p<0.05). The monounsaturated fatty acid (MUFA) content showed the highest (p<0.05) levels in CB. In contrast, the polyunsaturated fatty acid (PUFA) contents of breast meat, including linoleic acid (C18:2 ω6) and arachidonic acid (C20:4 ω6), were higher (p<0.05) in EM and WB than in CB. In conclusion, the EM and WB had less growth performances in comparison with CB, but they each had some unique features (taste, flavor, and physiological characteristics) when raised under the identical rearing and feeding conditions. PMID:26761496

  11. On the surging potential of polar ice streams: Part 2, Ice streams and physical characteristics of the Ross Sea drainage basin, West Antarctica

    SciTech Connect

    Jenssen, D.; Budd, W.F.; Smith, I.N.; Radok, U.

    1985-01-01

    The West Antarctic region from which ice drains into the Ross Sea is described and analyzed on a twenty km grid with the assumption that the ice is in a steady state of zero overall mass balance. The most striking features of the basin are five major ice streams moving in their lower reaches with velocities two orders of magnitude larger than the ice in which they are embedded. These high velocities are produced by driving stresses which markedly decrease downstream; this suggests that basal sliding takes over from internal deformation as dominant mode of flow. Algebraic expressions for both velocity components are given in terms of the downslope driving (or basal shear) stress, the ice thickness excess above the maximum thickness that can float on rock below mean sea level (''thickness above buoyancy''), and the basal temperature. Thus computed the velocities agree broadly with those derived directly from the condition of steady-state mass conservation (''balance velocities'') but there remain large local discrepancies. The latter fully define the three-dimensional strain rate fields and permit the residence times and ages of the ice to be estimated. They also enter into solutions of thermodynamic energy balance equations which give the temperatures in the ice and define regions where basal melting can be expected to occur for different values of the geothermal heat flux. The associated melt water layer is the key feature for a deeper understanding of the sliding and surging processes in ice streams and for improving the agreement between modeled and observed ice velocities.

  12. Paleocene and Maastrichtian calcareous nannofossils from clasts in Pleistocene glaciomarine muds from the northern James Ross Basin, western Weddell Sea, Antarctica

    USGS Publications Warehouse

    Kulhanek, D.K.

    2007-01-01

    Site NBP0602A-9, drilled during the SHALDRIL II cruise of the RV/IB Nathaniel B. Palmer, includes two holes located in the northern James Ross Basin in the western Weddell Sea, very close to the eastern margin of the Antarctic Peninsula. Sediment from both holes consists of very dark grey, pebbly, sandy mud, grading to very dark greenish grey, pebbly, silty mud in the lower 2.5 m of the second hole. In addition to abundant pebbles found throughout the cores, both holes contain numerous sedimentary clasts. Biostratigraphic analysis of diatom assemblages from the glaciomarine muds yields rare to few, poorly preserved diatoms. The mixed assemblage consists mostly of extant species, but also includes reworked taxa that range to the Miocene. The absence of Rouxia spp., however, suggests the sediment is late Pleistocene in age. The sedimentary clasts, on the other hand, are nearly barren of diatoms, but contain rare, moderately to well-preserved calcareous nannofossils. The clasts contain three distinct assemblages. Two clasts are assigned an early Maastrichtian age based on the presence of Biscutum magnum and Nephrolithus corystus, while one clast yields a late Maastrichtian age based on the presence of Nephrolithus frequens. These samples also contain other characteristic Late Cretaceous species, including Biscutum notaculum, Cribrosphaerella daniae, Eiffellithus gorkae, Kamptnerius magnificus, and Prediscosphaera bukryi. Two samples yield an early Paleocene assemblage dominated by Hornibrookina teuriensis. The Maastrichtian assemblages are similar to those found in the López de Bertodano Formation on Seymour and Snow Hill Islands, making it the likely source area for the Cretaceous clast material. Although no calcareous nannofossils have been reported from Paleocene formations on these islands, the occurrence of calcareous foraminifers suggests other calcareous plankton may be present; thus the Paleocene clasts likely also originated from the Seymour Island area.

  13. Uranium in river water

    SciTech Connect

    Palmer, M.R. ); Edmond, J.M. )

    1993-10-01

    The concentration of dissolved uranium has been determined in over 250 river waters from the Orinoco, Amazon, and Ganges basins. Uranium concentrations are largely determined by dissolution of limestones, although weathering of black shales represents an important additional source in some basins. In shield terrains the level of dissolved U is transport limited. Data from the Amazon indicate that floodplains do not represent a significant source of U in river waters. In addition, the authors have determined dissolved U levels in forty rivers from around the world and coupled these data with previous measurements to obtain an estimate for the global flux of dissolved U to the oceans. The average concentration of U in river waters is 1.3 nmol/kg, but this value is biased by very high levels observed in the Ganges-Brahmaputra and Yellow rivers. When these river systems are excluded from the budget, the global average falls to 0.78 nmol/kg. The global riverine U flux lies in the range of 3-6 [times] 10[sup 7] mol/yr. The major uncertainty that restricts the accuracy of this estimate (and that of all other dissolved riverine fluxes) is the difficulty in obtaining representative samples from rivers which show large seasonal and annual variations in runoff and dissolved load.

  14. Linking landscapes and habitat suitability scores for diadromous fish restoration in the susquehanna river basin

    USGS Publications Warehouse

    Kocovsky, P.M.; Ross, R.M.; Dropkin, D.S.; Campbell, J.M.

    2008-01-01

    Dams within the Susquehanna River drainage, Pennsylvania, are potential barriers to migration of diadromous fishes, and many are under consideration for removal to facilitate fish passage. To provide useful input for prioritizing dam removal, we examined relations between landscape-scale factors and habitat suitability indices (HSIs) for native diadromous species of the Susquehanna River. We used two different methods (U.S. Fish and Wildlife Service method: Stier and Crance [1985], Ross et al. [1993a, 1993b, 1997], and Pardue [1983]; Pennsylvania State University method: Carline et al. [1994]) to calculate HSIs for several life stages of American shad Alosa sapidissima, alewives Alosa pseudoharengus, and blueback herring Alosa aestivalis and a single HSI for American eels Anguilla rostrata based on habitat variables measured at transects spaced every 5 km on six major Susquehanna River tributaries. Using geographical information systems, we calculated land use and geologic variables upstream from each transect and associated those data with HSIs calculated at each transect. We then performed canonical correlation analysis to determine how HSIs were linked to geologic and land use factors. Canonical correlation analysis identified the proportion of watershed underlain by carbonate rock as a positive correlate of HSIs for all species and life stages except American eels and juvenile blueback herring. We hypothesize that potential mechanisms linking carbonate rock to habitat suitability include increased productivity and buffering capacity. No other consistent patterns of positive or negative correlation between landscape-scale factors and HSIs were evident. This analysis will be useful for prioritizing removal of dams in the Susquehanna River drainage, because it provides a broad perspective on relationships between habitat suitability for diadromous fishes and easily measured landscape factors. This approach can be applied elsewhere to elucidate relationships

  15. Modeling river delta formation.

    PubMed

    Seybold, Hansjörg; Andrade, José S; Herrmann, Hans J

    2007-10-23

    A model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced by using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore, our model is capable of simulating the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi River. PMID:17940031

  16. Nile River Delta, Egypt

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The Nile River Delta of Egypt (30.0N, 31.0E) irrigated by the Nile River and its many distributaries, is some of the richest farm land in the world and home to some 45 million people, over half of Egypt's population. The capital city of Cairo is at the apex of the delta. Just across the river from Cairo can be seen the ancient three big pyramids and sphinx at Giza and the Suez Canal is just to the right of the delta.

  17. Modeling river delta formation

    PubMed Central

    Seybold, Hansjörg; Andrade, José S.; Herrmann, Hans J.

    2007-01-01

    A model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced by using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore, our model is capable of simulating the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi River. PMID:17940031

  18. BELLE FOURCHE RIVER WATERSHED ASSESSMENT

    EPA Science Inventory

    The Belle Fourche River is a natural stream that drains portions of Butte, Lawrence, and Meade Counties in South Dakota and flows to the Cheyenne River in Meade County. The river receives runoff from agricultural operations and both the river and its tributaries have experienced...

  19. River basin management

    SciTech Connect

    Newsome, D.H.; Edwards, A.M.C.

    1984-01-01

    The quality of water is of paramount importance in the management of water resources - including marine waters. A quantitative knowledge of water quality and the factors governing it is required to formulate and implement strategies requiring an inter-disciplinary approach. The overall purpose of this conference was to bring together the latest work on water quality aspects of river basin management. These proceedings are structured on the basis of five themes: problems in international river basins; the contribution of river systems to estuarial and marine pollution; the setting of standards; monitoring; and practical water quality management including use of mathematical models. They are followed by papers from the workshop on advances in the application of mathematical modelling to water quality management, which represent some of the current thinking on the problems and concepts of river basin management.

  20. Santa Cruz River Options

    EPA Science Inventory

    This presentation summarizes qualitative research insights gained during development of a nonmarket valuation survey for changes to the Santa Cruz River in Southern Arizona. Qualitative research provides an important avenue for understanding how the public interprets valuation s...

  1. Colorado River Delta

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Colorado River ends its 2330 km journey in the Gulf of Mexico in Baja California. The heavy use of the river as an irrigation source for the Imperial Valley has dessicated the lower course of the river in Mexico such that it no longer consistently reaches the sea. Prior to the mid 20th century, the Colorado River Delta provided a rich estuarine marshland that is now essentially desiccated, but nonetheless is an important ecological resource.

    The image was acquired May 29, 2006, covers an area of 44.3 x 57.5 km, and is located at 32.1 degrees north latitude, 115.1 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  2. River Meander Studies

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.

    1972-01-01

    The meander patterns of the Feather and Colorado rivers were studied in an attempt to correlate pattern changes and flood probability. Attempts were also made to correlate stream meander power spectrum and stream discharge frequency distribution.

  3. Mackenzie River Delta, Canada

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Mackenzie River in the Northwest Territories, Canada, with its headstreams the Peace and Finley, is the longest river in North America at 4241 km, and drains an area of 1,805,000 square km. The large marshy delta provides habitat for migrating Snow Geese, Tundra Swans, Brant, and other waterfowl. The estuary is a calving area for Beluga whales. The Mackenzie (previously the Disappointment River) was named after Alexander Mackenzie who travelled the river while trying to reach the Pacific in 1789.

    The image was acquired on August 4, 2005, covers an area of 55.8 x 55.8 km, and is located at 68.6 degrees north latitude, 134.7 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  4. Laminar laboratory rivers

    NASA Astrophysics Data System (ADS)

    Seizilles, Grégoire; Devauchelle, Olivier; Lajeunesse, Éric; Métivier, François

    2014-05-01

    A viscous fluid flowing over fine plastic grains spontaneously channelizes into a few centimeters-wide river. After reaching its equilibrium shape, this stable laboratory flume is able to carry a steady load of sediments, like many alluvial rivers. When the sediment discharge vanishes, the river size, shape and slope fit the threshold theory proposed by Glover and Florey (1951), which assumes that the Shields parameter is critical on the channel bed. As the sediment discharge is increased, the river widens and flattens. Surprisingly, the aspect ratio of its cross section depends on the sediment discharge only, regardless of the water discharge. We propose a theoretical interpretation of these findings based on the balance between gravity, which pulls particles towards the center of the channel, and the diffusion of bedload particles, which pushes them away from areas of intense bedload.

  5. THE GREAT RIVERS NEWSLETTER

    EPA Science Inventory

    The Great Rivers Newsletter is a periodic publication of the EPA's Mid-Continent Ecology Division. It is designed to disseminate timely information about the EMAP-GRE project among EPA investigators; state, federal, and tribal collaborators; and other stakeholders.

  6. Hood River Production Master Plan.

    SciTech Connect

    O'Toole, Patty

    1991-07-01

    The Northwest Power Planning Council's 1987 Columbia River Fish and Wildlife Program authorizes the development of artificial production facilities to raise chinook salmon and steelhead for enhancement in the Hood, Umatilla, Walla Walla, Grande Ronde and Imnaha rivers and elsewhere. On February 26, 1991 the Council agreed to disaggregate Hood River from the Northeast Oregon Hatchery Project, and instead, link the Hood River Master Plan (now the Hood River Production Plan) to the Pelton Ladder Project (Pelton Ladder Master Plan 1991).

  7. Connecticut River Hydrologic Observatory

    NASA Astrophysics Data System (ADS)

    Ballestero, T. P.

    2004-12-01

    The Connecticut River basin possesses some characteristics that make it unique for studying hydrologic issues that transcend scale. The watershed was first dramatically altered through natural processes (glaciation) and then heavily impacted by human stresses (dams, deforestation, acid precipitation/deposition), only to exhibit recent decades of return to a more natural state (reforestation, land conservation, stream restoration, pollution abatement, and dam removal). The watershed is sufficiently north to be classified as a cold region. More specifically to hydrology, the watershed exhibits the spectrum of flooding problems: ice dams, convective storms, hurricanes, rain on melting snow, and low pressure systems. The 28,000 square kilometer Connecticut River Watershed covers one third of the states of New Hampshire, Vermont, Massachusetts, and Connecticut. The >640-km long rivers' headwaters start on the Canadian border at the Fourth Connecticut Lake, and flows southward to discharge in Long Island sound. The lower 100 km of river are tidally influenced. The Connecticut River is responsible for 70 % of the freshwater inflow to Long Island Sound. The Connecticut River is a sixth order stream that exhibits a dendritic pattern in an elongated scheme. This setting therefore affords many first and second order streams in almost parallel fashion, flowing west or east towards the central Connecticut River spine. There are 38 major tributaries to the mainstem Connecticut River, and 26 of these tributaries drain greater than 250 square kilometers. There is in excess of 30,000 km of perennially flowing stream length in the watershed. For more information, see: http://www.unh.edu/erg/connho/

  8. The rivers of civilization

    NASA Astrophysics Data System (ADS)

    Macklin, Mark G.; Lewin, John

    2015-04-01

    The hydromorphic regimes that underpinned Old World river-based civilizations are reviewed in light of recent research. Notable Holocene climatic changes varied from region to region, whilst the dynamics of floodplain environments were equally diverse, with river channel changes significantly affecting human settlement. There were longer-term trends in Holocene hydroclimate and multi-centennial length 'flood-rich' and 'flood-poor' episodes. These impacted on five identified flooding and settlement scenarios: (i) alluvial fans and aprons; (ii) laterally mobile rivers; (iii) rivers with well-developed levees and flood basins; (iv) river systems characterised by avulsions and floodouts; and (v) large river-fed wetlands. This gave a range of changes that were either more or less regular or incremental from year-to-year (and thus potentially manageable) or catastrophic. The latter might be sudden during a flood event or a few seasons (acute), or over longer periods extending over many decades or even centuries (chronic). The geomorphic and environmental impacts of these events on riparian societies were very often irreversible. Contrasts are made between allogenic and autogenic mechanism for imposing environmental stress on riverine communities and a distinction is made between channel avulsion and contraction responses. Floods, droughts and river channel changes can precondition as well as trigger environmental crises and societal collapse. The Nile system currently offers the best set of independently dated Holocene fluvial and archaeological records, and the contrasted effects of changing hydromorphological regimes on floodwater farming are examined. The persistence of civilizations depended essentially on the societies that maintained them, but they were also understandably resilient in some environments (Pharaonic Egypt in the Egyptian Nile), appear to have had more limited windows of opportunity in others (the Kerma Kingdom in the Nubian Nile), or required

  9. Synthetic River Valleys

    NASA Astrophysics Data System (ADS)

    Brown, R.; Pasternack, G. B.

    2011-12-01

    The description of fluvial form has evolved from anecdotal descriptions to artistic renderings to 2D plots of cross section or longitudinal profiles and more recently 3D digital models. Synthetic river valleys, artificial 3D topographic models of river topography, have a plethora of potential applications in fluvial geomorphology, and the earth sciences in general, as well as in computer science and ecology. Synthetic river channels have existed implicitly since approximately the 1970s and can be simulated from a variety of approaches spanning the artistic and numerical. An objective method of synthesizing 3D stream topography based on reach scale attributes would be valuable for sizing 3D flumes in the physical and numerical realms, as initial input topography for morphodynamic models, stream restoration design, historical reconstruction, and mechanistic testing of interactions of channel geometric elements. Quite simply - simulation of synthetic channel geometry of prescribed conditions can allow systematic evaluation of the dominant relationships between river flow and geometry. A new model, the control curve method, is presented that uses hierarchically scaled parametric curves in over-lapping 2D planes to create synthetic river valleys. The approach is able to simulate 3D stream geometry from paired 2D descriptions and can allow experimental insight into form-process relationships in addition to visualizing past measurements of channel form that are limited to two dimension descriptions. Results are presented that illustrate the models ability to simulate fluvial topography representative of real world rivers as well as how channel geometric elements can be adjusted. The testing of synthetic river valleys would open up a wealth of knowledge as to why some 3D attributes of river channels are more prevalent than others as well as bridging the gap between the 2D descriptions that have dominated fluvial geomorphology the past century and modern, more complete, 3D

  10. Time-space focused intrusion of genetically unrelated arc magmas in the early Paleozoic Ross-Delamerian Orogen (Morozumi Range, Antarctica)

    NASA Astrophysics Data System (ADS)

    Rocchi, S.; Di Vincenzo, G.; Dini, A.; Petrelli, M.; Vezzoni, S.

    2015-09-01

    The growth of continental crust in accretionary orogenic belts takes place through repeated cycles of subduction-accretion of rock units from continental and oceanic magmatic arcs, supra-subduction zone backarcs and forearcs loaded with continent-derived materials. An ancient example relevant to magmatic arc accretion models is represented by the remnants of the Cambrian-Ordovician Ross Orogen in the Morozumi Range, Victoria Land (Antarctica). There, late Neoproterozoic phyllites host an intrusive complex which preserves a remarkably uncommon record of genetically unrelated magma pulses emplaced under a variable stress regime in a short time span: (1) a dominant K-feldspar-phyric granite, (2) fine-grained dioritic stocks and dykes, (3) a peraluminous granite; and (4) a tonalitic-granodioritic dyke swarm. Laserprobe U-Pb zircon dates cluster at late Cambrian times for all these units, yet they carry differential cargoes of relict cores. Unique geochemical-isotopic signatures for both the less evolved magmas (diorite and dyke tonalite) and the most acidic ones (granite and peraluminous granite) indicate that each one of them originated from distinct sources at depth. Additionally, field relationships and chemical evolutionary trends testify for a variety of shallow level open-system processes, such as magma mingling/mixing between diorite and main granite magmas, as well as progressive incorporation of the host schists by the dyke tonalite magma. In summary, crustal growth in the Morozumi intrusive complex was contributed by fresh mantle magma issuing from the metasomatised mantle wedge, while the production of other melts did recycle different crustal portions/layers: the main granite derived from Grenville-age granulitic lower crust; the peraluminous granite from late Proterozoic upper crust, and the tonalite magmas derived from subduction erosion-enriched subarc mantle and evolved by ingestion of local metasedimentary rocks. Overall, the Morozumi intrusive complex

  11. The roles of MCDW and deep water iron supply in sustaining a recurrent phytoplankton bloom on central Pennell Bank (Ross Sea)

    NASA Astrophysics Data System (ADS)

    Kustka, Adam B.; Kohut, Josh T.; White, Angelicque E.; Lam, Phoebe J.; Milligan, Allen J.; Dinniman, Michael S.; Mack, Stefanie; Hunter, Elias; Hiscock, Michael R.; Smith, Walker O.; Measures, Chris I.

    2015-11-01

    During January-February 2011 standing stocks of phytoplankton (chl a) in the Pennell Bank region of the Ross Sea were variable over 10-100 km spatial scales. One area of elevated chl a on central Pennell Bank (CPB) appeared to be a recurrent mid-summer feature. The western flank (WF) of Pennell Bank had pronounced signatures of Modified Circumpolar Deep Water (MCDW). We evaluated the spatial extent of Fe limitation and net primary production and tested whether MCDW may provide elevated amounts of Fe to the CPB region, through a combination of in situ measurements, shipboard incubations and a horizontally resolved physical model. Regional fluxes of dissolved Fe from deep to surface waters were compared to calculated Fe demands. Low in situ variable to maximum fluorescence (Fv/Fm; 0.24-0.37) and surface water dissolved Fe concentrations (~0.12-0.21 nM) were suggestive of widespread limitation, corroborated by the consistent responses (Fv/Fm, growth, and nutrient removal ratios) of incubation treatments to Fe addition. MCDW from the WF region had lower dissolved Fe concentrations than that measured in CDW (Circumpolar Deep Water), which suggests on-shelf modification with Fe deplete surface waters and is consistent with the lack of stimulation due to incubation amendments with filtered MCDW. Model results and empirical data suggest MCDW from the WF region is further modified and mixed en route to the CPB region, leading to both the erosion of the canonical MCDW signature and an elevated dissolved Fe inventory of CPB region deep water. This suggests the addition of Fe possibly via diagenesis, as suggested by Marsay et al. (2014). Calculated deep water supply rates to the surface waters of CPB were ~0.18-0.43 m d-1, while calculated rates at the WF or northern Pennell Bank (NPB) regions were negative. The CPB populations exhibited ~4.5-fold higher net production rates compared to those in the WF and NPB regions and required 520-3200 nmol Fe m-2 d-1. The modeled vertical

  12. Metamorphic and structural evidence for significant vertical displacement along the Ross Lake fault zone, a major orogen-parallel shear zone in the Cordillera of western North America

    USGS Publications Warehouse

    Baldwin, J.A.; Whitney, D.L.; Hurlow, H.A.

    1997-01-01

    Results of an investigation of the petrology and structure of the Skymo complex and adjacent terranes constrain the amount, timing, and sense of motion on a segment of the > 600-km-long Late Cretaceous - early Tertiary Ross Lake fault zone (RLFZ), a major orogen-parallel shear zone in the Cordillera of western North America. In the study area in the North Cascades, Washington state, the RLFZ accommodated significant pre-middle Eocene vertical displacement, and it juxtaposes the Skymo complex with upper amphibolite facies (650??-690??C and 6-7 kbar) Skagit Gneiss of the North Cascades crystalline core to the SW and andalusite-bearing phyllite of the Little Jack terrane (Intermontane superterrane) to the NE. The two main lithologic units of the Skymo complex, a primitive mafic intrusion and a fault-bounded block of granulite facies metasedimentary rocks, are unique in the North Cascades. Granulite facies conditions were attained during high-temperature (> 800??C), low pressure (??? 4 kbar) contact metamorphism associated with intrusion of the mafic magma. P-T estimates and reaction textures in garnet-orthopyroxene gneiss suggest that contact metamorphism followed earlier, higher pressure regional metamorphism. There is no evidence that the Skagit Gneiss experienced high-T - low-P contact metamorphism. In the Little Jack terrane, however, texturally late cordierite ?? spinel and partial replacement of andalusite by sillimanite near the terrane's fault contact with Skymo gabbro suggest that the Little Jack terrane experienced high-T (??? 600??C) - low-P (??? 4 kbar) contact metamorphism following earlier low-grade regional metamorphism. Similarities in the protoliths of metasedimentary rocks in the Skymo and Little Jack indicate that they may be part of the same terrane. Differences in pressure estimates for the Little Jack versus Skymo for regional metamorphism that preceded contact metamorphism indicate vertical displacement of ??? 10 km (west side up) on the strand

  13. Betsy Ross Can Be Dangerous.

    ERIC Educational Resources Information Center

    McLean, Harvard

    1979-01-01

    Annotates seven popular American cultural myths and explains how historical myths can serve as vehicles of misinformation in the social studies classroom. Presents tips to teachers on how to teach history in an open and honest manner without glamorizing historical figures. (Author/DB)

  14. Stable Isotopic signatures of Adélie penguin remains provide long-term paleodietary records in Northern Victoria Land (Ross Sea, Antarctica)

    NASA Astrophysics Data System (ADS)

    Lorenzini, Sandra; Baroni, Carlo; Fallick, Anthony Edward; Baneschi, Ilaria; Salvatore, Maria Cristina; Zanchetta, Giovanni; Dallai, Luigi

    2010-05-01

    The stable isotopes geochemistry of carbon and nitrogen provides a powerful tools for investigating in animal dietary patterns and shifts during the past. The signature of C and N isotopes provide direct information about the diet of an individual and its dietary patterns, especially when the dietary sources consist of prey from different trophic levels (i.e. different C and N isotopic composition) (DeNiro and Epstein 1978, Minawaga and Wada 1984, Koch et al. 1994, Hobson 1995). By analyzing the isotopic composition of penguin remains, we present a new detailed Adélie penguin (Pygoscelis adeliae) paleodietary record for the area of Terra Nova Bay (Victoria Land, Ross Sea). Adélie penguins primarily feed on fish (mainly the silverfish Pleuragramma antarcticum) and krill (Euphausia superba, Euphausia cristallorophias) (Ainley 2002, Lorenzini et al. 2009) that belonging to two different trophic levels. Consequently, they are characterized by different isotopic signatures. Specifically, we analyzed 13C/12C and 15N/14N ratios of more than one thousand of modern and fossil Adélie penguin eggshell and guano samples collected from ornithogenic soils (penguin guano-formed) dated back to ≈7,200 years BP (Baroni and Orombelli 1994, Lambert et al. 2002, Baroni and Hall 2004, Hall et al. 2006). The expanded database of stable isotope values obtained from Adélie penguin remains define a detailed paleodietary record with an excellent temporal continuity over all the investigated time period. Our data indicate a significant dietary shift between fish and krill, with a gradual decrease from past to present time in the proportion of fish compared to krill in Adélie penguin diet. From 7200 yrs BP to 2000 yrs BP, δ13C and δ15N values indicate fish as the most eaten prey. The dietary contribution of lower-trophic prey in penguin diet started becoming evident not earlier than 2000 yrs BP, when the δ13C values reveal a mixed diet based on fish and krill consumption. Modern

  15. The Nile River

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image of the northern portion of the Nile River was captured by MISR's nadir camera on January 30, 2001 (Terra orbit 5956). The Nile is the longest river in the world, extending for about 6700 kilometers from its headwaters in the highlands of eastern Africa. At the apex of the fertile Nile River Delta is the Egyptian capital city of Cairo. To the west are the Great Pyramids of Giza. North of here the Nile branches into two distributaries, the Rosetta to the west and the Damietta to the east. Also visible in this image is the Suez Canal, a shipping waterway connecting Port Said on the Mediterranean Sea with the Gulf of Suez. The Gulf is an arm of the Red Sea, and is located on the righthand side of the picture. Image credit: NASA/GSFC/LaRC/JPL, MISR Team.

  16. Alaskan river environmental acoustics

    NASA Astrophysics Data System (ADS)

    Dahl, Peter H.; Pfisterer, Carl; Geiger, Harold J.

    2005-04-01

    Sonars are used by the Alaska Department of Fish and Game (ADF&G) to obtain daily and hourly estimates of at least four species of migratory salmon during their seasonal migration which lasts from June to beginning of September. Suspended sediments associated with a river's sediment load is an important issue for ADF&G's sonar operations. Acoustically, the suspended sediments are a source of both volume reverberation and excess attenuation beyond that expected in fresh water. Each can impact daily protocols for fish enumeration via sonar. In this talk, results from an environmental acoustic study conducted in the Kenai River (June 1999) using 420 kHz and 200 kHz side looking sonars, and in the Yukon River (July 2001) using a 120 kHz side looking sonar, are discussed. Estimates of the volume scattering coefficient and attenuation are related to total suspended sediments. The relative impact of bubble scattering and sediment scattering is also discussed.

  17. Rivers of Evidence

    PubMed Central

    Adams, Clive E

    2013-01-01

    There has been too much of a one-way flow drift down a river of evidence. Researchers from rich countries have produced the primary evidence which they proceed to summarise within reviews. These summaries have directed care worldwide. However, things are changing and the river of evidence can flow in the other direction. The care of women with eclampsia has been changed or refined throughout the world because of a large low and middle income country trial. The global care of people with heart disease has been greatly modified by studies originating in China. The care of people who are acutely aggressive because of psychosis has to be reconsidered in the light of the evidence coming from Brazil and India. Healthcare is an issue everywhere and evaluation of care is not the premise of any one culture—the evidence—river must run both ways. PMID:24596880

  18. 33 CFR 207.380 - Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Red Lake River, Minn.; logging... Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls. (a) Parties wishing to run logs on Red Lake River must provide storage booms near the head of the river to take...

  19. 33 CFR 207.380 - Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Red Lake River, Minn.; logging... Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls. (a) Parties wishing to run logs on Red Lake River must provide storage booms near the head of the river to take...

  20. 76 FR 36447 - Safety Zone; Patuxent River, Patuxent River, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-22

    ..., 2008, issue of the Federal Register (73 FR 3316). Public meeting We do not now plan to hold a public... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Patuxent River, Patuxent River, MD AGENCY... a temporary safety zone during the ``NAS Patuxent River Air Expo '11'', which consists of...

  1. Regional river sulfur runoff

    SciTech Connect

    Husar, R.B.; Husar, J.D.

    1985-01-20

    The water and sulfur runoff data for 54 large river basins were assembled, covering 65% of the nondesert land area of the world. The sulfur concentration ranges from 0.5 mg S/L for the West African rivers Niger and Volta to 100 mg S/L in the Colorado River; the world average is 3.2 mg S/L. The concentrations in central and eastern Europe as well as central and eastern North America exceed 8 mg S/L. The sulfur runoff density is also highest in the river basins over these industrialized regions, exceeding 2 g S/m/sup 2//yr. However, high sulfur runoff density in excess of 3 g S/m/sup 2//yr is also measured over the Pacific islands New Zealand and New Guinea and the archipelagos of Indonesia and the Philippines. The natural background sulfur runoff was estimated by assuming that South America, Africa, Australia, and the Pacific Islands are unperturbed by man and that the average river sulfur concentration is in the range 1--3 mg S/L. Taking these background concentration values, the man-induced sulfur runoff for Europe ranges between 2 and 8 times the natural flow, and over North America, man's contribution ranges between 1 and 5 times the natural runoff. The global sulfur flow from nondesert land to the oceans and the Caspian Sea is estimated as 131 Tg S/yr, of which 46--85 Tg S/yr is attributed to natural causes. The regional river sulfur runoff pattern discussed in this paper does not have enough spatial resolution to be directly applicable to studies of the environmental effects of man-induced sulfur flows. However, it points to the continental-size regions where those perturbations are most evident and to the magnitude of the perturbations as expressed in units of the natural flows.

  2. Regional river sulfur runoff

    NASA Astrophysics Data System (ADS)

    Husar, Rudolf B.; Husar, Janja Djukic

    1985-01-01

    The water and sulfur runoff data for 54 large river basins were assembled, covering 65% of the nondesert land area of the world. The sulfur concentration ranges from 0.5 mg S/L for the West African rivers Niger and Volta to 100 mg S/L in the Colorado River; the world average is 3.2 mg S/L. The concentrations in central and eastern Europe as well as central and eastern North America exceed 8 mg S/L. The sulfur runoff density is also highest in the river basins over these industrialized regions, exceeding 2 g S/m2/yr. However, high sulfur runoff density in excess of 3 g S/m2/yr is also measured over the Pacific islands New Zealand and New Guinea and the archipelagos of Indonesia and the Philippines. The natural background sulfur runoff was estimated by assuming that South America, Africa, Australia, and the Pacific Islands are unperturbed by man and that the average river sulfur concentration is in the range 1-3 mg S/L. Taking these background concentration values, the man-induced sulfur runoff for Europe ranges between 2 and 8 times the natural flow, and over North America, man's contribution ranges between 1 and 5 times the natural runoff. The global sulfur flow from nondesert land to the oceans and the Caspian Sea is estimated as 131 Tg S/yr, of which 46-85 Tg S/yr is attributed to natural causes. The regional river sulfur runoff pattern discussed in this paper does not have enough spatial resolution to be directly applicable to studies of the environmental effects of man-induced sulfur flows. However, it points to the continental-size regions where those perturbations are most evident and to the magnitude of the perturbations as expressed in units of the natural flows.

  3. Osmium in the rivers

    SciTech Connect

    Sharma, M. |; Wasserburg, G.J.

    1997-12-01

    There is a large uncertainty in our understanding of the behavior of osmium during weathering and transport into deep oceans and the osmium budget of the oceans. The problem stems chiefly from the lack of osmium data on the dissolved load in the rivers and in the estuaries. In this study, the concentration and isotopic composition of osmium have been determined in three North American rivers (the Mississippi, the Columbia, and the Connecticut) and one river draining central Europe and flowing into the Baltic Sea (the Vistula). Osmium concentration in the Mississippi and the Vistula is about 45 femto mol kg{sup -1}; it is about 14 and 15 femto mol kg{sup -1} for the Connecticut and the Columbia, respectively. The {sup 187}Os/{sup 186}Os ratios estimated for the Mississippi and the Vistula are 10.4 and 10.7, respectively. For the Connecticut and the Columbia {sup 187}Os/{sup 186}Os = 8.8 and 14.4, respectively. Of all the rivers examined, the Mississippi is by far the largest, supplying {approximately}1.6% of the total annual world river flow. Its osmium isotopic composition is identical to the upper Mississippi valley loesses indicating (1) congruent dissolution of the bedrock and (2) little or no impact of anthropogenic sources on the osmium isotopic composition of the dissolved load. The latter observation indicates that the upper limit of the anthropogenic input in the dissolved osmium load of the Mississippi outflow is about 250 g yr{sup -1}. While the osmium concentration of the Vistula is high the isotopic composition does not appear to have been affected by substantial pollution. The river data can be used to put limits on the mean residence time of osmium in the oceans ({bar {tau}}{sub Os}) and on the osmium budget of the oceans. 17 refs., 1 fig., 1 tab.

  4. River Pollution: Part I.

    ERIC Educational Resources Information Center

    Openshaw, Peter

    1983-01-01

    Describes a unit on river pollution and analytical methods to use in assessing temperature, pH, flow, calcium, chloride, dissolved oxygen, biochemical oxygen demand, dissolved nitrogen, detergents, heavy metals, sewage pollution, conductivity, and sediment cores. Suggests tests to be carried out and discusses significance of results. (JM)

  5. Savannah River Site Robotics

    ScienceCinema

    None

    2012-06-14

    Meet Sandmantis and Frankie, two advanced robotic devices that are key to cleanup at Savannah River Site. Sandmantis cleans hard, residual waste off huge underground storage tanks. Frankie is equipped with unique satellite capabilities and sensing abilties that can determine what chemicals still reside in the tanks in a cost effective manner.

  6. Ecological River Basin Management.

    ERIC Educational Resources Information Center

    Smith, Anthony Wayne

    Addressing the Seventh American Water Resources Conference, Washington, D. C., October, 1971, Anthony Wayne Smith, President, National Parks and Conservation Association, presents an expose on how rivers should be managed by methods which restores and preserve the natural life balances of the localities and regions through which they flow. The…

  7. Nissitissit River Investigation.

    ERIC Educational Resources Information Center

    Sweatman, Jon

    Prepared for the student participant, this manual guides a day's exploration of the Nissitissit River. The unit, one of several developed in conjunction with Project Exploration, has the broad goals of promoting--through experiential learning in a variety of environments outside the classroom--the student's self-confidence and ability to work…

  8. Colwater fish in rivers

    EPA Science Inventory

    A standard sampling protocol to assess the fish assemblages and abundances in large, coldwater rivers is most accurate and precise if consistent gears and levels of effort are used at each site. This requires thorough crew training, quality control audits, and replicate sampling...

  9. Discover the Nile River

    ERIC Educational Resources Information Center

    Project WET Foundation, 2009

    2009-01-01

    Bordering on the Fantastic. As the longest river on earth, the Nile passes through 10 countries. Presented through a wide range of activities and a winning array of games, it's also unsurpassed at taking young minds into exploring the world of water, as well as natural and man made wonders.

  10. River on Trial

    ERIC Educational Resources Information Center

    Carney, Thomas R.

    1972-01-01

    Presents controversy over damming of Wyoming's Upper Green River to supply water to the arid basins of eastern Wyoming. Possibilities of wildlife destruction, flooding of valley lands, and opposition to the construction of the Kendall Dam itself are enumerated together with legislative action to date. (BL)

  11. The River Rock School.

    ERIC Educational Resources Information Center

    Gereaux, Teresa Thomas

    1999-01-01

    In the early 1920s, the small Appalachian community of Damascus, Virginia, used private subscriptions and volunteer labor to build a 15-classroom school made of rocks from a nearby river and chestnut wood from nearby forests. The school building's history, uses for various community activities, and current condition are described. (SV)

  12. The Nation's Rivers

    ERIC Educational Resources Information Center

    Wolman, M. Gordon

    1971-01-01

    Illustrates difficulties in measuring long term changes in water temperature and content of dissolved oxygen, inorganic ions, radiation, pesticides, and trash and debris by reference to selected U. S. river systems. Concludes that observations to detect polluters may not provide data for assessing trends and trend reversals. (AL)

  13. Savannah River Site Robotics

    SciTech Connect

    2010-01-01

    Meet Sandmantis and Frankie, two advanced robotic devices that are key to cleanup at Savannah River Site. Sandmantis cleans hard, residual waste off huge underground storage tanks. Frankie is equipped with unique satellite capabilities and sensing abilties that can determine what chemicals still reside in the tanks in a cost effective manner.

  14. A 100-year Reconstruction of Regional Sea Ice Extent in the Ross and Amundsen-Bellingshausen Seas as Derived from the RICE Ice Core, Coastal West Antarctica

    NASA Astrophysics Data System (ADS)

    Emanuelsson, D. B.; Bertler, N. A. N.; Baisden, W. T.; Keller, E. D.

    2014-12-01

    Antarctic sea ice increased over the past decades. This increase is the result of an increase in the Ross Sea (RS) and along the coast of East Antarctica, whereas the Amundsen-Bellingshausen Seas (ABS) and the Antarctic Peninsula has seen a general decline. Several mechanisms have been suggested as drivers for the regional, complex sea ice pattern, which include changes in ocean currents, wind pattern, as well as ocean and atmospheric temperature. As part of the Roosevelt Island Climate Evolution (RICE) project, a 763 m deep ice core was retrieved from Roosevelt Island (RI; W161° 21', S79°41', 560 m a.s.l.), West Antarctica. The new record provides a unique opportunity to investigate mechanism driving sea ice variability in the RS and ABS sectors. Here we present the water stable isotope record (δD) from the upper part of the RICE core 0-40 m, spanning the time period from 1894 to 2011 (Fig. 1a). Annual δD are correlated with Sea Ice Concentration (SIC). A significant negative (r= -0.45, p≤ 0.05) correlation was found between annual δD and SIC in the eastern RS sector (boxed region in Fig. 1b) for the following months NDJFMA (austral summer and fall). During NDJFMA, RI receives local moisture input from the RS, while during the rest of the year a large extent of this local moisture source area will be covered with sea ice with the exception of the RS Polynya. Concurrently, we observe positive δD and SIC correlations in the ABS, showing a dipole pattern with the eastern RS. For this reason, we suggest that the RICE δD might be used as a proxy for past SIC for the RS and ABS region. There is no overall trend in δD over 100 years (r= -0.08 ‰ dec-1, p= 0.81, 1894-2011). However, we observe a strong increase from 2000-2011 of 17.7 ‰ dec-1(p≤ 0.1), yet the recent δD values and trend of the last decade are not unprecedented (Fig. 1a). We investigate changes in sea surface temperature, atmospheric temperature, inferred surface ocean currents and

  15. The Offshore New Harbor (ONH) Seismic Expedition: Revealing the Stratigraphic History in the Southern McMurdo Sound Region, Ross Sea, Antarctica from the Greenhouse to Icehouse Worlds

    NASA Astrophysics Data System (ADS)

    Pekar, S. F.; Speece, M. A.; Wilson, G. S.; Sunwall, D. A.; Tinto, K. J.

    2010-12-01

    down dip of CIROS-1. The Oligocene strata are characterized by a clinoformal geometry, with reflectors down lapping onto the two prominent reflectors that correspond to the Eocene / Oligocene Boundary and the “mid” Oligocene hiatus recognized in the CIROS-1 borehole. These new data support the idea that substantial Eocene and Oligocene strata can be recovered by drilling east of the location of the CIROS-1 borehole. The upper units imaged below the base of CIROS-1 represent the potential for future drilling objectives for the ANDRILL Program. Additionally, reflectors that contained trough-like shapes were interpreted as representing incised valleys, which were most likely cut by ice streams. These valleys provide prima facie documentation of when the ice sheet extended beyond the present-day coastline. These reflectors were correlated to CIROS-1 as well as the ANDRILL AND-2A borehole, providing ages on the timing of major ice stream advances of the East Antarctic Ice Sheet in the western Ross Sea area.

  16. Variation of dissolved organic carbon transported by two Chinese rivers: The Changjiang River and Yellow River.

    PubMed

    Liu, Dong; Pan, Delu; Bai, Yan; He, Xianqiang; Wang, Difeng; Zhang, Lin

    2015-11-15

    Real-time monitoring of riverine dissolved organic carbon (DOC) and the associated controlling factors is essential to coastal ocean management. This study was the first to simulate the monthly DOC concentrations at the Datong Hydrometric Station for the Changjiang River and at the Lijin Hydrometric Station for the Yellow River from 2000 to 2013 using a multilayer back-propagation neural network (MBPNN), along with basin remote-sensing products and river in situ data. The average absolute error between the modeled values and in situ values was 9.98% for the Changjiang River and 10.84% for the Yellow River. As an effect of water dilution, the variations of DOC concentrations in the two rivers were significantly negatively affected by discharge, with lower values reported during the wet season. Moreover, vegetation growth status and agricultural activities, represented by the gross primary product (GPP) and cropland area percent (CropPer) in the river basin, respectively, also significantly affected the DOC concentration in the Changjiang River, but not the Yellow River. The monthly riverine DOC flux was calculated using modeled DOC concentrations. In particular, the riverine DOC fluxes were affected by discharge, with 71.06% being reported for the Changjiang River and 90.71% for the Yellow River. Over the past decade, both DOC concentration and flux in the two rivers have not shown significant changes. PMID:26404069

  17. 3. ENVIRONMENT, FROM SOUTH, SHOWING RIVER ROAD RIDGE CARRYING CASSELMAN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. ENVIRONMENT, FROM SOUTH, SHOWING RIVER ROAD RIDGE CARRYING CASSELMAN RIVER ROAD OVER CASSELMAN RIVER - River Road Bridge, Crossing Casselman River on Casselman River Road, Grantsville, Garrett County, MD

  18. Chronic Fatigue Syndrome (CFS): Causes

    MedlinePlus

    ... Ross River Fever, a mosquito-borne tropical disease Coxiella burnetti , the agent that causes Q fever Human ... with Epstein-Barr virus, Ross River virus, and Coxiella burnetti will lead to a post-infective condition ...

  19. Hood River Passive House

    SciTech Connect

    Hales, D.

    2013-03-01

    The Hood River Passive Project was developed by Root Design Build of Hood River Oregon using the Passive House Planning Package (PHPP) to meet all of the requirements for certification under the European Passive House standards. The Passive House design approach has been gaining momentum among residential designers for custom homes and BEopt modeling indicates that these designs may actually exceed the goal of the U.S. Department of Energy's (DOE) Building America program to reduce home energy use by 30%-50% (compared to 2009 energy codes for new homes). This report documents the short term test results of the Shift House and compares the results of PHPP and BEopt modeling of the project.

  20. Chesapeake Bay, Potomac River

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The nation's capital lies astride the Potomac River (38.5N, 77.5W) at the head of the Potomac Estuary. Baltimore, MD, also in the scene, is connected to Washington by the Baltimore-Washington Parkway. The suburbs of both cities tend to cluster around the Washington and Baltimore Beltways. Most of the countryside in the eastern two-thirds of this scene is either heavily forested or is in farming, dairy operations or poultry production.

  1. Onilahy River, Madagascar

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Near the southern tip of Madagascar, the Onilahy River (23.5S, 44E) drains a near barren landscape, the result of rapid deforestation for quick profits from the lumber industry with no regard to the environmental impact. At the turn of the century, the island was a lush tropical paradise with about 90 percent of the surface forested. Now, at the close of the century, only about 10 percent of the forests remain in inaccessible rugged terrain.

  2. River networks as biodiversity hotlines.

    PubMed

    Décamps, Henri

    2011-05-01

    For several years, measures to insure healthy river functions and to protect biodiversity have focused on management at the scale of drainage basins. Indeed, rivers bear witness to the health of their drainage basins, which justifies integrated basin management. However, this vision should not mask two other aspects of the protection of aquatic and riparian biodiversity as well as services provided by rivers. First, although largely depending on the ecological properties of the surrounding terrestrial environment, rivers are ecological systems by themselves, characterized by their linearity: they are organized in connected networks, complex and ever changing, open to the sea. Second, the structure and functions of river networks respond to manipulations of their hydrology, and are particularly vulnerable to climatic variations. Whatever the scale considered, river networks represent "hotlines" for sharing water between ecological and societal systems, as well as for preserving both systems in the face of global change. River hotlines are characterized by spatial as well as temporal legacies: every human impact to a river network may be transmitted far downstream from its point of origin, and may produce effects only after a more or less prolonged latency period. Here, I review some of the current issues of river ecology in light of the linear character of river networks. PMID:21640951

  3. 77 FR 30589 - SteelRiver Infrastructure Partners LP, SteelRiver Infrastructure Associates LLC, SteelRiver...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-23

    ... Surface Transportation Board SteelRiver Infrastructure Partners LP, SteelRiver Infrastructure Associates LLC, SteelRiver Infrastructure Fund North America LP, and Patriot Funding LLC--Control Exemption--Patriot Rail Corp., et al. SteelRiver Infrastructure Partners LP (SRIP LP), SteelRiver...

  4. 50 CFR 226.205 - Critical habitat for Snake River sockeye salmon, Snake River fall chinook salmon, and Snake River...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of the USGS publication and maps may be... salmon, Snake River fall chinook salmon, and Snake River spring/summer chinook salmon. 226.205 Section... Snake River sockeye salmon, Snake River fall chinook salmon, and Snake River spring/summer...

  5. 50 CFR 226.205 - Critical habitat for Snake River sockeye salmon, Snake River fall chinook salmon, and Snake River...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of the USGS publication and maps may be... salmon, Snake River fall chinook salmon, and Snake River spring/summer chinook salmon. 226.205 Section... Snake River sockeye salmon, Snake River fall chinook salmon, and Snake River spring/summer...

  6. Flooding on Elbe River

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Heavy rains in Central Europe over the past few weeks have led to some of the worst flooding the region has witnessed in more than a century. The floods have killed more than 100 people in Germany, Russia, Austria, Hungary, and the Czech Republic and have led to as much as $20 billion in damage. This false-color image of the Elbe River and its tributaries was taken on August 20, 2002, by the Moderate Resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite. The floodwaters that inundated Dresden, Germany, earlier this week have moved north. As can be seen, the river resembles a fairly large lake in the center of the image just south of the town of Wittenberg. Flooding was also bad further downriver in the towns of Maqgdeburge and Hitzacker. Roughly 20,000 people were evacuated from their homes in northern Germany. Fifty thousand troops, border police, and technical assistance workers were called in to combat the floods along with 100,000 volunteers. The floodwaters are not expected to badly affect Hamburg, which sits on the mouth of the river on the North Sea. Credit:Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  7. Flooding along Danube River

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Heavy rains in Central and Eastern Europe over the past few weeks have led to some of the worst flooding the region has witnessed in over a century. The floods have killed more than 100 people in Germany, Russia, Austria, Hungary and the Czech Republic and have led to as much as $20 billion in damage. This false-color image of the Danube River and its tributaries was taken on August 19, 2002, by the Moderate Resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite. Budapest, the capital of Hungary, sits just south of the large bend in the river at the top of the image. Here the water reached levels not seen since 1965. Fortunately, the riverbanks are lined with 33-foot retainer walls throughout the city, so it did not face the same fate as Dresden or Prague along the Elbe River. But as one can see, the floodwaters hit many rural areas farther south. As last reported, the water was receding along the Danube. Credit: Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC.

  8. Tsunami Impacts in River Environments

    NASA Astrophysics Data System (ADS)

    Tolkova, E.; Tanaka, H.; Roh, M.

    2014-12-01

    The 2010 Chilean and the 2011 Tohoku tsunami events demonstrated the tsunami's ability to penetrate much farther along rivers than the ground inundation. At the same time, while tsunami impacts to the coastal areas have been subject to countless studies, little is known about tsunami propagation in rivers. Here we examine the field data and conduct numerical simulations to gain better understanding of the tsunami impacts in rivers.The evidence which motivated our study is comprised of water level measurements of the aforementioned tsunamis in multiple rivers in Japan, and the 2011 Tohoku and some other tsunamis in the Columbia River in the US. When the available tsunami observations in these very different rivers are brought together, they display remarkably similar patterns not observed on the open coast. Two phenomena were discovered in the field data. First, the phase of the river tide determines the tsunami penetration distance in a very specific way common to all rivers. Tsunami wave progressively disappears on receding tide, whereas high tide greatly facilitates the tsunami intrusion, as seen in the Figure. Second, a strong near-field tsunami causes substantial and prolonged water accumulation in lower river reaches. As the 2011 tsunami intruded rivers in Japan, the water level along rivers rose 1-2 m and stayed high for many hours, with the maximum rise occurring several km from the river mouth. The rise in the water level at some upstream gaging stations even exceeded the tsunami amplitude there.Using the numerical experiments, we attempt to identify the physics behind these effects. We will demonstrate that the nonlinear interactions among the flow components (tsunami, tide, and riverine flow) are an essential condition governing wave dynamics in tidal rivers. Understanding these interactions might explain some previous surprising observations of waves in river environments. Figure: Measurements of the 2010/02/27 tsunami along Naruse and Yoshida rivers

  9. Fluoride in UK rivers.

    PubMed

    Neal, Colin; Neal, Margaret; Davies, Helen; Smith, Jennifer

    2003-10-01

    Fluoride concentrations in eastern UK rivers (the Humber, Tweed, Wear, Great Ouse and Thames) are described based on information collected within the Land-Ocean Interaction Study (LOIS) and by the Environment Agency (EA) of England and Wales. The results show varied fluoride concentrations across the region, with a range from <0.01 to >10 mg l(-1); and mean, median and range in mean concentrations of 0.30, 0.21 and 0.05-3.38 mg l(-1) (excluding one outlier point), respectively. Within the main rivers and tributaries, the mean fluoride concentration varied from approximately 0.5 to over 2 mg l(-1) and the highest values occurred within the Don basin (Don, Dearne and Rother) and parts of the Trent basin (upper Tame and mid-upper Derbyshire Derwent) in highly industrialised and urbanised areas (Sheffield and Rotherham in the Don basin; Birmingham and Derby on the Trent). For localised inputs to the rivers, fluoride concentrations were slightly higher, and considerably higher in one outlier case. Correspondingly, the other rivers examined typically had mean fluoride concentrations between approximately 0.2 and 0.5 mg l(-1), but fluoride concentrations were lower in the headwater areas. As there is much less information on fluoride levels in upland areas, extensive data collected as part of an acid waters survey are used to show that fluoride concentrations are generally less than 0.1 mg l(-1) for the upland UK. The data are summarised in terms of both fluoride concentrations and flux, and the values are cross-referenced to other determinands collected within LOIS. The high positive correlation with boron and negative correlation with flow show the importance of point source (sewage) inputs of fluoride, while strong positive correlations between fluoride and barium indicate the relative importance of vein mineralisation in the bedrock in supplying fluoride to the waters of the Yorkshire Ouse and its tributaries. There seems to be some process that limits the fluoride

  10. 33 CFR 125.06 - Western rivers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Western rivers. 125.06 Section... VESSELS § 125.06 Western rivers. The term western rivers as used in the regulations in this subchapter shall include only the Red River of the North, the Mississippi River and its tributaries above the...

  11. 33 CFR 125.06 - Western rivers.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Western rivers. 125.06 Section... VESSELS § 125.06 Western rivers. The term western rivers as used in the regulations in this subchapter shall include only the Red River of the North, the Mississippi River and its tributaries above the...

  12. 33 CFR 125.06 - Western rivers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Western rivers. 125.06 Section... VESSELS § 125.06 Western rivers. The term western rivers as used in the regulations in this subchapter shall include only the Red River of the North, the Mississippi River and its tributaries above the...

  13. 33 CFR 125.06 - Western rivers.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Western rivers. 125.06 Section... VESSELS § 125.06 Western rivers. The term western rivers as used in the regulations in this subchapter shall include only the Red River of the North, the Mississippi River and its tributaries above the...

  14. Rehabilitating China's largest inland river.

    PubMed

    Li, Yiqing; Chen, Yaning; Zhang, Yaoqi; Xia, Yang

    2009-06-01

    Wetlands are particularly important for conserving China's biodiversity but riparian wetlands in the Tarim River basin in western China have been reduced by 46% during the last 3 decades. The world's largest habitat for Populus euphratica, which is in the Tarim River basin, significantly shrank. To protect and restore the deteriorated ecosystems along the Tarim River and its associated wetlands, China's government initiated a multimillion dollar river restoration project to release water from upper dams to the dried-up lower reaches of the Tarim River starting in 2000. We monitored the responses of groundwater and vegetation to water recharge in the lower reaches of the river from 2000 to 2006 by establishing nine 1000-m-long transects perpendicular to the river at intervals of 20-45 km along the 320-km river course below the Daxihaizi Reservoir, the source of water conveyance, to Lake Taitema, the terminus of the Tarim River. Water recharges from the Daxihaizi Reservoir to the lower reaches of the Tarim River significantly increased groundwater levels and vegetation coverage at all monitoring sites along the river. The mean canopy size of the endangered plant species P. euphratica doubled after 6 years of water recharge. Some rare migrating birds returned to rest on the restored wetlands in summer along the lower reaches of the Tarim River. The biggest challenge facing decision makers, however, is to balance water allocation and water rights between agricultural and natural ecosystems in a sustainable way. A large number of inhabitants in the Tarim Basin depend on these limited water resources for a living. At the same time, the endangered ecosystems need to be protected. Given the ecological, socioeconomic, and sociopolitical realities in the Tarim Basin, adaptive water policies and strategies are needed for water allocation in these areas of limited water resources. PMID:22748091

  15. Trinity river basin, Texas

    USGS Publications Warehouse

    Ulery, Randy L.; Van Metre, Peter C.; Crossfield, Allison S.

    1993-01-01

    In 1991 the Trinity River Basin National Water-Quality Assessment (NAWQA) will include assessments of surface-water and ground-water quality. Initial efforts have focused on identifying water-quality issues in the basin and on the environmental factors underlying those issues. Physical characteristics described include climate, geology, soils, vegetation, physiography, and hydrology. Cultural characteristics discussed include population distribution, land use and land cover, agricultural practices, water use, an reservoir operations. Major water-quality categories are identified and some of the implications of the environmental factors for water quality are presented.

  16. Methane Emission from Tropical Rivers

    NASA Astrophysics Data System (ADS)

    Sawakuchi, H. O.; Rasera, M. F. F. L.; Krusche, A. V.; Ballester, M. V. R.

    2012-04-01

    Inland water is already known as an important source of methane to atmosphere. Methane is produced in anaerobic environments usually find in lakes and floodplain bottom sediment. It is the main reason that almost all information regarding methane flux come from this environments. However, while floodplain dries during low water season reducing methanogenesis, rivers keep the capacity to emit methane throughout the year. Here we present preliminary results of CH4 flux measurements done in 6 large tropical rivers within the Amazon basin. We measured 17 areas using floating chamber during dry (low water) season, between September and November of 2011, in Amazon river mainstem, Araguaia, Xingu, Tapajós, Madeira, and Negro Rivers. Measured fluxes of all rivers ranged from 59.3 to 2974.4 mmol m-2 yr-1. Geomorphologic structure of channels is one important factor that contributes to this high heterogeneity due to development of low flow velocity depositional settings allowing formation of anoxic zones in rivers. Hydraulic and sediment barriers in the confluence of river channels promote the generation of natural dams which function as a trap for the suspension load favoring the deposition of organic rich muds. This kind of environment is very different from common river channels and has a stronger potential of methane emission. Average values of our flux measurements for this two river environments show that depositional areas can have much higher fluxes than the main channel, 1089.6 and 163.1 mmol m-2 yr-1, respectively. Hence, CH4 flux from these depositional zones is similar to some tropical floodplain lakes and reservoirs. Although the low flux from channel, the area covered by water is very large resulting in a significant contribution to the regional methane emission to the atmosphere. Moreover, mapping the area of these depositional river zones will give us a better idea of the magnitude of methane flux from tropical rivers.

  17. River Capture in Disequilibrium Landscapes

    NASA Astrophysics Data System (ADS)

    McCoy, S. W.; Perron, J.; Willett, S.; Goren, L.

    2013-12-01

    The process of river piracy or river capture has long drawn interest as a potential mechanism by which drainage basins large and small evolve towards an equilibrium state. River capture transfers both drainage area and drainage lines from one river basin to another, which can cause large, abrupt shifts in network topology, drainage divide positions, and river incision rates. Despite numerous case studies in which river capture has been proposed to have occurred, there is no general, mechanistic framework for understanding the controls on river capture, nor are there quantitative criteria for determining if capture has occurred. Here we use new metrics of landscape disequilibrium to first identify landscapes in which drainage reorganization is occurring. These metrics are based on a balance between an integral of the contributing drainage area and elevation. In an analysis of rivers in the Eastern United States we find that many rivers are in a state of disequilibrium and are experiencing recent or ongoing area exchange between basins. In these disequilibrium basins we find widespread evidence for network rearrangement via river capture at multiple scales. We then conduct numerical experiments with a 2-D landscape evolution model to explore the conditions in which area exchange among drainage basins is likely to occur as discrete capture events as opposed to continuous divide migration. These experiments indicate that: (1) capture activity increases with the degree of disequilibrium induced by persistent spatial gradients in tectonic forcing or by temporal changes in climate or tectonic forcing; (2) capture activity is strongly controlled by the initial planform drainage network geometry; and (3) capture activity scales with the fluvial incision rate constant in the river power erosion law.

  18. 33 CFR 117.865 - Clatskanie River.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... after each day's authorized commercial fishing period established by the Columbia River Compact (Washington State Department of Fisheries and the Fish Commission of Oregon) for the Columbia River...

  19. 33 CFR 117.865 - Clatskanie River.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... after each day's authorized commercial fishing period established by the Columbia River Compact (Washington State Department of Fisheries and the Fish Commission of Oregon) for the Columbia River...

  20. 33 CFR 117.865 - Clatskanie River.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... after each day's authorized commercial fishing period established by the Columbia River Compact (Washington State Department of Fisheries and the Fish Commission of Oregon) for the Columbia River...

  1. 33 CFR 117.865 - Clatskanie River.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... after each day's authorized commercial fishing period established by the Columbia River Compact (Washington State Department of Fisheries and the Fish Commission of Oregon) for the Columbia River...

  2. Always a River. Activity Booklet.

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Cincinnati, OH.

    This activity booklet was designed to accompany a floating barge exhibition entitled "Always a River" that brought together the experiences of the past, the opportunities of the present, and the hopes of the future afforded by the Ohio River. The interdisciplinary activities in this booklet aim at enriching the lives of young people and making…

  3. INDIAN RIVER LAGOON IR, 2004

    EPA Science Inventory

    Since the Indian River Lagoon Program's last implementation review, the NEP through the local sponsorship of the St. Johns River Water Management District, has seen a three-fold increase in implementation funding from $6.7 million in 1999, to $21.3 million in FY 2003. This fundin...

  4. Treasure Along the Parker River.

    ERIC Educational Resources Information Center

    Fitzpatrick, Ann-Marie; And Others

    Designed so that 100 to 125 heterogeneously grouped 7th and 8th grade students and a team of 5 core teachers might experience and discover the natural and historical "treasure" in the Parker River area of Massachusetts, this interdisciplinary unit centers on a hike to Parker River (6.7 miles) and visits to a cemetery, a monument, and Old Town…

  5. Flooding on Russia's Lena River

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Nearly every year in the late spring, ice blocks the flow of water at the mouth of the Lena River in northeastern Russia and gives rise to floods across the Siberian plains. This year's floods can be seen in this image taken on June 2, 2002, by the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Terra satellite. The river runs down the left side of the image, and its delta is shrouded in ice (red) at the top of the image. Normally, the river would resemble a thin black line in MODIS imagery. The river, which is Russia's longest, flows 2,641 miles (4,250 kilometers) south to north through Siberia and into the Laptev Sea. In the winter, the river becomes nearly frozen. In the spring, however, water upstream thaws earlier than water at the mouth of the river. As the southern end of the river begins to melt, blocks of ice travel downstream to the still frozen delta, pile up, and often obstruct the flow of water. Flooding doesn't always occur on the same parts of the river. The floods hit further south last year. If the flooding grows severe enough, explosive charges are typically used to break up the ice jams. In these false-color images land areas are a dull, light green or tan, and water is black. Clouds appear pink, and ice comes across as bright red. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  6. Hood River Passive House

    SciTech Connect

    Hales, D.

    2014-01-01

    The Hood River Passive Project was developed by Root Design Build of Hood River Oregon using the Passive House Planning Package (PHPP) to meet all of the requirements for certification under the European Passive House standards. The Passive House design approach has been gaining momentum among residential designers for custom homes and BEopt modeling indicates that these designs may actually exceed the goal of the U.S. Department of Energy's (DOE) Building America program to reduce home energy use by 30%-50% (compared to 2009 energy codes for new homes). This report documents the short term test results of the Shift House and compares the results of PHPP and BEopt modeling of the project. The design includes high R-Value assemblies, extremely tight construction, high performance doors and windows, solar thermal DHW, heat recovery ventilation, moveable external shutters and a high performance ductless mini-split heat pump. Cost analysis indicates that many of the measures implemented in this project did not meet the BA standard for cost neutrality. The ductless mini-split heat pump, lighting and advanced air leakage control were the most cost effective measures. The future challenge will be to value engineer the performance levels indicated here in modeling using production based practices at a significantly lower cost.

  7. Hood River Passive House

    SciTech Connect

    Hales, David

    2014-01-01

    The Hood River Passive Project was developed by Root Design Build of Hood River Oregon using the Passive House Planning Package (PHPP) to meet all of the requirements for certification under the European Passive House standards. The Passive House design approach has been gaining momentum among residential designers for custom homes and BEopt modeling indicates that these designs may actually exceed the goal of the U.S. Department of Energy's (DOE) Building America program to "reduce home energy use by 30%-50% (compared to 2009 energy codes for new homes). This report documents the short term test results of the Shift House and compares the results of PHPP and BEopt modeling of the project. The design includes high R-Value assemblies, extremely tight construction, high performance doors and windows, solar thermal DHW, heat recovery ventilation, moveable external shutters and a high performance ductless mini-split heat pump. Cost analysis indicates that many of the measures implemented in this project did not meet the BA standard for cost neutrality. The ductless mini-split heat pump, lighting and advanced air leakage control were the most cost effective measures. The future challenge will be to value engineer the performance levels indicated here in modeling using production based practices at a significantly lower cost.

  8. Geomorphology and River Dynamics of the Lower Copper River, Alaska

    USGS Publications Warehouse

    Brabets, Timothy P.; Conaway, Jeffrey S.

    2009-01-01

    Located in south-central Alaska, the Copper River drains an area of more than 24,000 square miles. The average annual flow of the river near its mouth is 63,600 cubic feet per second, but is highly variable between winter and summer. In the winter, flow averages approximately 11,700 cubic feet per second, and in the summer, due to snowmelt, rainfall, and glacial melt, flow averages approximately 113,000 cubic feet per second, an order of magnitude higher. About 15 miles upstream of its mouth, the Copper River flows past the face of Childs Glacier and enters a large, broad, delta. The Copper River Highway traverses this flood plain, and in 2008, 11 bridges were located along this section of the highway. The bridges cross several parts of the Copper River and in recent years, the changing course of the river has seriously damaged some of the bridges. Analysis of aerial photography from 1991, 1996, 2002, 2006, and 2007 indicates the eastward migration of a channel of the Copper River that has resulted in damage to the Copper River Highway near Mile 43.5. Migration of another channel in the flood plain has resulted in damage to the approach of Bridge 339. As a verification of channel change, flow measurements were made at bridges along the Copper River Highway in 2005-07. Analysis of the flow measurements indicate that the total flow of the Copper River has shifted from approximately 50 percent passing through the bridges at Mile 27, near the western edge of the flood plain, and 50 percent passing through the bridges at Mile 36-37 to approximately 5 percent passing through the bridges at Mile 27 and 95 percent through the bridges at Mile 36-37 during average flow periods. The U.S. Geological Survey's Multi-Dimensional Surface-Water Modeling System was used to simulate water-surface elevation and velocity, and to compute bed shear stress at two areas where the Copper River is affecting the Copper River Highway. After calibration, the model was used to examine the

  9. Indicators for transboundary river management.

    PubMed

    Lorenz, C M; Gilbert, A J; Cofino, W P

    2001-07-01

    The aim of this paper is to analyze the potential of indicators for integrated river basin management and to develop a set of indicators for the management of transboundary river basins. An indicator, comprising a variable or some aggregation of variables, describes a system or process such that it has significance beyond the face value of its components. Integrated river basin management takes into account policies and measures for the multifunctional use of rivers on a catchment scale and associated institutional changes. Indicators are useful instruments for this process for two reasons. Firstly, they meet the information need of policy- and decision-makers. Secondly, indicators can be used to structure the definition and description of information needs and collection of information between the different international, institutional, and sectoral management levels. The development of indicators involves a number of steps: definition of aim, construction of conceptual model, selection of variables, comparison with selection criteria, database assessment, and indicator selection. In this paper these steps are discussed and specified for integrated river basin management. This results in a set of indicators describing the pressure to the river, the state of the river ecosystem, the impact to goods and services provided by the river, and the societal response. The proposed set of indicators measured at a river basin scale provides integrated information on the use and supply of goods and services, underlying cause-effect relationships and possible trade-offs and their spatial distribution (e.g., upstream versus downstream). Furthermore, we propose a division of tasks and responsibilities for river basin management with regard to the development of indicators, data collection, and their application in decision-making. PMID:11436995

  10. 6. SANDY RIVER BRIDGE AT TROUTDALE, EAST ELEVATION, LOOKING 306 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. SANDY RIVER BRIDGE AT TROUTDALE, EAST ELEVATION, LOOKING 306 DEGREES NORTHWEST. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  11. 3. SANDY RIVER BRIDGE AT TROUTDALE, NORTH END, LOOKING 184 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. SANDY RIVER BRIDGE AT TROUTDALE, NORTH END, LOOKING 184 DEGREES SOUTH. SAME PHOTO AS OR-36-2. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  12. 7. SANDY RIVER BRIDGE AT TROUTDALE, PERSPECTIVE LOOKING EAST. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. SANDY RIVER BRIDGE AT TROUTDALE, PERSPECTIVE LOOKING EAST. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  13. 1. SANDY RIVER BRIDGE AT TROUTDALE, SOUTH END, LOOKING 18 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. SANDY RIVER BRIDGE AT TROUTDALE, SOUTH END, LOOKING 18 DEGREES NORTH. SAME PHOTO AS OR-36-1. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  14. 2. SANDY RIVER BRIDGE AT TROUTDALE, SOUTH END, LOOKING 20 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. SANDY RIVER BRIDGE AT TROUTDALE, SOUTH END, LOOKING 20 DEGREES NORTH. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  15. 5. SANDY RIVER BRIDGE AT TROUTDALE, EAST ELEVATION DETAIL, LOOKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. SANDY RIVER BRIDGE AT TROUTDALE, EAST ELEVATION DETAIL, LOOKING 6 DEGREES NORTH. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  16. 4. SANDY RIVER BRIDGE AT TROUTDALE, NORTH END, LOOKING 224 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. SANDY RIVER BRIDGE AT TROUTDALE, NORTH END, LOOKING 224 DEGREES SOUTHWEST. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  17. River network routing in all rivers of the Texas Gulf

    NASA Astrophysics Data System (ADS)

    David, C. H.; Maidment, D. R.; Hong, S.; Niu, G.; Yang, Z.

    2009-12-01

    The mapped rivers and streams of the contiguous United States are available in a high resolution geographic information system (GIS) dataset called NHDPlus. This hydrographic dataset has about 3 million river and water body reaches along with information on how they are connected into networks. A river network model called RAPID is developed for the NHDPlus river network and applied to the 68,143 river reaches of the entire Texas Gulf, whose lateral inflow to the river network is calculated by a land surface model. RAPID allows for a matrix-based calculation of flow and volume of water in all reaches of a river network, with many thousands of reaches. Gages from the USGS National Water Information System are used to assess the quality of model calculations and to automatically determine optimal model parameters with about 1 gage available for each 160 reaches simulated. RAPID is adapted for parallel computing and has been tested on the Lonestar supercomputer (http://www.tacc.utexas.edu/resources/hpcsystems/) although challenges related to parallel computing are significant. The first author was awarded the 2008 Horton (Hydrology) Research Grant for this work.

  18. River-Based Experiential Learning: the Bear River Fellows Program

    NASA Astrophysics Data System (ADS)

    Rosenberg, D. E.; Shirley, B.; Roark, M. F.

    2012-12-01

    The Department of Civil and Environmental Engineering, Outdoor Recreation, and Parks and Recreation programs at Utah State University (USU) have partnered to offer a new, unique river-based experiential learning opportunity for undergraduates called the Bear River Fellows Program. The program allows incoming freshmen Fellows to experience a river first hand during a 5-day/4-night river trip on the nearby Bear River two weeks before the start of their first Fall semester. As part of the program, Fellows will navigate the Bear River in canoes, camp along the banks, interact with local water and environmental managers, collect channel cross section, stream flow, vegetation cover, and topological complexity data, meet other incoming freshmen, interact with faculty and graduate students, develop boating and leadership skills, problem solve, and participate as full members of the trip team. Subsequently, Fellows will get paid as undergraduate researchers during their Fall and Spring Freshman semesters to analyze, synthesize, and present the field data they collect. The program is a collaborative effort between two USU academic units and the (non-academic) division of Student Services and supports a larger National Science Foundation funded environmental modelling and management project for the lower Bear River, Utah watershed. We have advertised the program via Facebook and emails to incoming USU freshmen, received 35 applications (60% women), and accepted 5 Fellows into the program (3 female and 2 male). The river trip departs August 14, 2012. The poster will overview the Bear River Fellows Program and present qualitative and preliminary outcomes emerging from the trip and Fellows' work through the Fall semester with the field data they collect. We will also undertake more rigorous and longer longitudinal quantitative evaluation of Program outcomes (for example, in problem-solving and leadership) both in Spring 2013 and in subsequent 2013 and 2014 offerings of the

  19. Will the Atchafalaya River Capture the Lower Mississippi River?

    NASA Astrophysics Data System (ADS)

    Edmonds, D.

    2011-12-01

    The Old River Control Structure (ORCS) was built in the 1960s to prevent the Atchafalaya River from capturing the lower Mississippi River. The 2011 flood on the Mississippi River tested ORCS and renewed concerns about what would happen to the rivers if ORCS failed. Most consider capture a foregone conclusion if ORCS failed, but this hypothesis has never been tested. A viable alternative hypothesis is that the discharge distribution between the Atchafalaya and Mississippi would stabilize at the relative proportions predicted by recent theory such that both channels transmit water. To test these hypotheses I conducted numerical experiments of the Mississippi-Atchafalaya rivers in the absence of ORCS using Delft3D. All model runs have evolving beds and are depth-integrated. The grid is 2D in planform and follows the banks of each river. The channel walls are fixed, tributaries are not included, and there are no floodplains. At the upstream boundary I specify the water discharge and sediment fluxes. The incoming discharge carries two grain sizes, one noncohesive (200 microns) and one cohesive (15 microns). At the downstream boundaries water surface elevations are set to zero. The initial bed topography in each river comes from 2004 and 2006 hydrographic surveys of the Mississippi and Atchafalaya, respectively. I conducted 7 experiments where the discharge upstream of ORCS (Qup) is steady, but varies among experiments from 5000 m3 s-1 to 50000 m3 s-1. Results show that the response of the rivers depends strongly on Qup. When Qup > 15000 m3 s-1 there is net flow capture by the Atchafalaya, and the capture rate increases with increasing Qup. But when Qup < 15000 m3 s-1 there is net flow capture by the Mississippi. The rates of capture for different values of Qup can be used to calculate if capture would occur for a realistic, unsteady hydrograph.

  20. Constraints on ice volume changes of the WAIS and Ross Ice Shelf since the LGM based on cosmogenic exposure ages in the Darwin-Hatherton glacial system of the Transantarctic Mountains

    NASA Astrophysics Data System (ADS)

    Fink, David; Storey, Bryan; Hood, David; Joy, Kurt; Shulmeister, James

    2010-05-01

    Quantitative assessment of the spatial and temporal scale of ice volume change of the West Antarctic ice sheet (WAIS) and Ross Ice Shelf since the last glacial maximum (LGM) ~20 ka is essential to accurately predict ice sheet response to current and future climate change. Although global sea level rose by approximately 120 metres since the LGM, the contribution of polar ice sheets is uncertain and the timing of any such contribution is controversial. Mackintosh et al (2007) suggest that sectors of the EAIS, similar to those studied at Framnes Mountains where the ice sheet slowly calves at coastal margins, have made marginal contributions to global sea-level rise between 13 and 7 ka. In contrast, Stone et al (2003) document continuing WAIS decay during the mid-late Holocene, raising the question of what was the response of the WAIS since LGM and into the Holocene. Terrestrial evidence is restricted to sparse coastal oasis and ice free mountains which archive limits of former ice advances. Mountain ranges flanking the Darwin-Hatherton glaciers exhibit well-defined moraines, weathering signatures, boulder rich plateaus and glacial tills, which preserve the evidence of advance and retreat of the ice sheet during previous glacial cycles. Previous studies suggest a WAIS at the LGM in this location to be at least 1,000 meters thicker than today. As part of the New Zealand Latitudinal Gradient Project along the Transantarctic, we collected samples for cosmogenic exposure dating at a) Lake Wellman area bordering the Hatherton Glacier, (b) Roadend Nunatak at the confluence of the Darwin and Hatherton glaciers and (c) Diamond Hill which is positioned at the intersection of the Ross Ice Shelf and Darwin Glacier outlet. While the technique of exposure dating is very successful in mid-latitude alpine glacier systems, it is more challenging in polar ice-sheet regions due to the prevalence of cold-based ice over-riding events and absence of outwash processes which removes